Target feature integrated laser field and amplifier compensation system

ABSTRACT

An Integrated Laser Field and Amplifier Compensation System (ILFACS) for end-to-end compensation of high-energy laser for propagation through turbulence with non-cooperative target are described. ILFACS using interferometric slaving technique and stand-alone adaptive optical systems to effect pre-compensation of amplitude and phase aberrations in turbulent medium, providing pre-compensation for aberrations in a laser amplifier is presented. ILFACS enables integration with a short pulse mode locked laser for use in Target Feature Adaptive Optics (TFAO) or with a mode locked ultra short pulse laser with carrier envelope phase stabilization for use in Broadband Coherent Adaptive Optics (BCAO).

CLAIM OF BENEFIT

This application is divisional application claiming benefit ofnon-provisional application Ser. No. 12/962,163 filed Dec. 7, 2010 andalso to provisional application No. 61/285,471 filed Dec. 10, 2009.

FIELD OF INVENTION

The present invention relates to a method and several systemimplementations for projection of laser beams through a turbulent mediumwith a non-cooperative target using a combination of an adaptive opticalsystem and a transform limited short pulse laser source to form acontrollable focused laser beacon at the target. A non-cooperativetarget refers to a target in which no laser beacon is provided directlyby the target for wavefront sensing.

BACKGROUND OF THE INVENTION

Adaptive optical system technology has found a wide range ofapplications including astronomical imaging and long-range free spaceoptical communication. Adaptive optical system technology canpotentially enhance any application in which turbulence along the path,which leads to refractive index fluctuations due to temperaturevariations, degrades the performance of an imaging or laser projectionsystem. Prior art methods are well known for dealing with greatdistances and associated phenomena of strong scintillation (whereinbranch points in the phase function begin to dominate performance andamplitude fluctuations can begin to degrade performance). See referencesbelow. (1; 2; 3; 4; 5; 6; 7; 8; 9; 10). These methods suffer from twoimportant limitations that prevent ready application for higher energylaser and directed energy applications: (1) a requirement that the phasecorrection device be capable of operating with a high power laser; and(2) significantly reduced effectiveness with a non-cooperative target[with the method described in reference 9 below being an exception].

On the topic of the first limitation—that the phase correction device becapable of operation with a high power laser—there are two drivingissues at hand. The first driving issue is that the coating technologyused to enable highly reflective coatings is at odds with the need tomake the facesheet of the phase correction device very thin to enablerapid and effective correction of aberrations. The stress induced by thehighly reflective coating utilized to prevent thermal inducedaberrations in the correction device can lead to such strong aberrationsthat the phase correction device is rendered un-usable. However, if amore conventional low stress coating is utilized the thermal aberrationsin the phase correction device can render the phase correction deviceun-usable. The second driving issue is that the difficulties associatedwith coating the phase correction device are typically alleviated bymaking the high power beam path physically larger to reduce the powerdensity on the phase correction device. This has many consequences andas the beam path grows in size the total size of the system growstremendously, leading to very heavy systems whose size is un-necessarilylarger to accommodate an adaptive optical system. A method that couldavoid compensation in the high power beam path and perform all higherorder correction functions in a low power beam path would have greatbenefit for a broad range of applications including long range laserradar, laser range-finding, and directed energy—these applications wouldbecome viable if high performance small size correction devices could beutilized.

On the topic of the second limitation—that the vast majority of methodsare not effective with non-cooperative targets—there has been somerecent headway made against this problem (see reference 9; 11), howeverthe practical implementation of such methods remains challenging. In thetypical/ideal scenario, a cooperative point source beacon projected fromthe target is used to make wavefront sensing measurements of thedistortions along the path for pre-compensation of a laser beam by theadaptive optical system. However, many potential applications ofadaptive optical systems, including laser radar, laser range finding,directed energy, and ophthalmic imaging all have “non-cooperative”targets. In the non-cooperative target case, no laser beacon isavailable from the target except that obtained from back-scatteredradiation from the target itself or from the atmosphere (laser guidestar obtained from Rayleigh or Mie light scattering). Many fundamentalchallenges exist in the case of a non-cooperative target. Overcomingthese challenges would have significant benefit for many applicationsand open up the enabling capability for adaptive optical systems to newregimes and applications.

What is needed is a method for simultaneous compensation of aberrationsin a high energy laser and for propagation through a turbulent mediumwith a cooperative or non-cooperative target. The present inventionmeets these needs by providing a method offering tremendous potentialimprovements both in terms of performance enhancements withnon-cooperative targets and in reduction in size, weight, and power of ahigh energy laser system due to reductions in size, weight, andcomplexity of the beam control system.

U.S. patent application Ser. No. 12/234,041 filed Sep. 19, 2008 is fullyincorporated herein by reference and provides a wavefront sensing andcontrol technique to measure the aberrations along the propagation pathusing return from an ultra-short coherence length laser forming acontrollable focused laser beacon at a non-cooperative target,regardless of the surface depth of the target. The present inventionprovides for an alternate but similar method for wavefront sensing andcontrol using return from lasers with a short, but not necessarilyultra-short pulse, where the requirement for the pulse and correspondingcoherence length is based on the target shape and orientation.

REFERENCES

-   1. Evaluation of phase-shifting approaches for a point-diffraction    interferometer with the mutual coherence function. Barchers, J. D.    and Rhoadarmer, T. A. December 2002, Applied Optics, Vol. 41, pp.    7499-7509.-   2. Improved compensation of amplitude and phase fluctuations by    means of multiple near field phase adjustments. Barchers, J. D. and    Ellerbroek, B. L. February 2001, Journal of the Optical Society of    America A, Vol. 18, pp. 399-411.-   3. Closed loop stable control of two deformable mirrors for    compensation of amplitude and phase fluctuations. Barchers, J. D.    2002, Journal of the Optical Society of America A, Vol. 19, pp.    926-945.-   4. Evaluation of the impact of finite resolution effects on    scintillation compensation using two deformable mirrors.    Barchers, J. D. 2001, Journal of the Optical Society of America A,    Vol. 18, pp. 3098-3109.-   5. Optimal control of laser beams for propagation through a    turbulent medium. Barchers, J. D. and Fried, D. L. September 2002,    Journal of the Optical Society of America A., Vol. 19, pp.    1779-1793.-   6. Barchers, J. D. Optimal beam propagation system having adaptive    optical systems. U.S. Pat. No. 6,638,291, Jan. 27, 2004.-   7. -. Electro-optical field conjugation system. Ser. No. 6452146,    Sep. 17, 2002.-   8. -. Non-cooperative laser target enhancement system and method.    Application U.S. patent Ser. No. 12/234,041, Sep. 19, 2008.-   9. Noise analysis for complex field estimation using a    self-referencing interferometer wavefront sensor. Rhoadarmer, T. A.    and Barchers, J. D. 2002, Proc. SPIE, Vol. 4825, pp. 215-227.-   10. Barchers, J. D. System and method for correction of turbulence    effects on laser or other transmission. U.S. Pat. No. 7,402,785,    Jul. 22, 2008.-   11. Belenkii, M. S. Beaconless adaptive optics system. Application    Ser. No. 12157014, Jun. 6, 2008.-   12. Modeling of laser beam control systems using projections onto    constraint sets. Barchers, J. D. 2004. American Control Conference.

SUMMARY OF THE INVENTION

The primary aspect of the present invention is to provide an integratedlaser field conjugation system method to measure and correct foraberrations in both a laser amplifier or laser resonator.

Another aspect of the present invention is to provide for propagationthrough turbulence utilizing phase correction devices that are only inlow power beam paths, greatly reducing the size, weight, power, andcomplexity of a directed energy system, regardless of the application.

Another aspect of the present invention is to provide a method for theability to form a narrowly focused beam at the target that can be usedfor high quality wavefront sensing measurements.

Yet another aspect of the present invention is to provide a method for anarrowly focused sensing beam at the target that provides the optimalapproach for wavefront sensing utilizing heterodyne detection tominimize the wavefront sensing error due to detector noise.

Another aspect of the present invention is to provide a method forsensing and pre-compensation of laser aberrations by having a beam pathfor imaging, tracking, and aim-point maintenance/control that is notcorrupted by aberrations from atmospheric turbulence.

Another aspect of the present invention is to provide a method such thatthe compensation for laser aberrations does not corrupt the imagery.

Other aspects of this invention will appear from the followingdescription and appended claims, reference being made to theaccompanying drawings forming a part of this specification wherein likereference characters designate corresponding parts in the several views.

The present invention provides a method for pre-compensation ofaberration in the laser gain medium, including potential methods forintegration with high energy lasers in both a master oscillator poweramplifier and unstable resonator configuration. These methods includemeans for joint pre-compensation of aberrations focusing less on thedescription of the method for obtaining a high quality wavefront sensingbeacon. The present invention also provides methods for compensationwith a non-cooperative target by obtaining a high quality wavefrontsensing beacon beam at the target. Numerical results demonstrating theeffectiveness of the method and a summary of the potential benefits willbe described below.

A summary of the present invention can also be described with referenceto the Figures below. The summary consisting of the following:

1. (FIGS. 6, 9, and 12) An electro-optical system for projection oflaser beams through a turbulent medium to a non-cooperative target, thesystem comprising:

-   -   a) a master oscillator beam having an optical path to an        amplifier means;    -   b) said amplifier means forming a high energy laser (HEL) beam        to a target via an optical path;    -   c) said optical path including a steering mirror and a        telescope;    -   d) a mode locked beacon master oscillator that produces a        majority beacon beam comprising a high repetition rate (ranging        from about 100 to 100000 Hz) sequence of transform limited        pulsed laser beams and producing a minority reference beam that        has a repetition rate defined by the cavity length of the mode        locked beacon master oscillator (ranging typically from MHz to        GHz);    -   e) wherein a timing delay circuit receives the minority        reference beam and produces a delayed reference beam that is        delayed to coincide with the arrival of a return beacon beam        from a target aimpoint along a propagation path axis;    -   f) said majority beacon beam transmitted via an optical path to        a medium power amplifier which sends the majority beacon beam        via an optical path to the target;    -   g) wherein a return beacon beam comprising a high repetition        rate pulse train beam returns from the target through the        turbulent medium, telescope, optical path, and a quarter        waveplate in the optical path, then passes through a first        polarizing beam splitter optic;    -   h) wherein the return beacon beam is then directed to a first        beacon wave front sensor (WFS) where it is combined with the        minority reference beam to form a composite beam for phase        measurement;    -   i) said first WFS controlling a first phase correction and        steering device pair which (1) corrects the majority beacon beam        with respect to phase aberrations caused by propagation through        the Turbulent medium and (2) provides phase commands to the        first phase correction and steering device pair that will result        in correction of amplitude aberrations in the beacon beam caused        by propagation through the turbulent medium;    -   j) a tracker and aim point controller which receives an image of        the target from an illumination source, thereby generating a        control signal to control the steering mirror;    -   k) said minority reference beacon beam further comprising a        sample which goes to a second beacon WFS which also receives a        sample of the returning beacon beam after said returning beacon        beam passes through a further propagation optics and a third and        second correction and steering device pair;    -   l) said second beacon WFS controlling a third correction and        steering device pair which corrects for remaining aberrations in        the return beacon beam, resulting in correction of both        amplitude and phase aberrations caused by propagation through        the turbulent medium;    -   m) a third WFS receives a sample beam from the minority master        oscillator beam after it passes through a spatial filter optic        and the fourth correction and steering device pair to compare to        a sample of the majority master oscillator beam after it passes        through an optical path including a propagation optics and the        third correction and steering device pair;    -   n) said third WFS controlling a fourth correction and steering        device pair to correct for aberrations induced by propagation        through the third phase correction and steering device pair and        propagation optics;    -   o) a fourth WFS receiving a sample of the majority master        oscillator beam and a minority master oscillator beam after it        passes through a spatial filter optic and the second correction        and steering device pair;    -   p) said fourth WFS controlling a second phase correction and        steering device pair to correct for aberrations in the master        oscillator;    -   q) a fifth WFS receiving a HEL amplifier probe beam after it        passes through the amplifier means; and    -   r) said fifth WFS controlling a fifth correction and steering        device pair.        2. The system of claim 1, wherein the first and fourth pair of        phase correction and steering device pairs are optically        conjugate to one another.        3. The system of claim 1, wherein the second and third pair of        phase correction and steering device pairs are optically        conjugate to one another.        4. The system of claim 1, wherein the second and third pair of        phase correction and steering device pairs have a free space        propagation distance (from the conjugate plane of the first and        fourth phase correction and steering device pairs) of        approximately:        −D ² /λN    -   where D is the beam size, λ is the wavelength and N is the        number of phase correction device actuator spacings across the        beam.        5. The system of claim 1, wherein the beacon beam is formed as a        cooperative beacon located at the target and pointed toward the        transmitting HEL optical path.        6. The system of claim 1, wherein the beacon beam is formed as        an illuminator beam launched from an auxiliary telescope to        illuminate the target, and the reflection from the target serves        as the beacon beam.        7. The system of claim 1, wherein the beacon beam is a solar        illumination of the target.        8. The system of claim 1, wherein the beacon beam is a thermal        emission of the target.        9. The system of claim 1, wherein the amplifier means is an        injection locked laser resonator.        10. The system of claim 1, wherein the image of the target is        formed as a cooperative beacon located at the target and pointed        toward the transmitting HEL optical path.        11. The system of claim 1, wherein the image of the target        received by the aim point controller is either a passive or        active illumination of the target.        12. The system of claim 1, wherein a sixth WFS receives a beacon        amplifier probe beam after it passes through a beacon medium        power amplifier and also receives a sample beam from the beacon        amplifier probe beam.        13. The system of claim 12, wherein the sixth WFS controls a        sixth correction and steering device pair.        14. The system of claim 1, wherein the amplifier means is a high        power laser amplifier.        15. The system of claim 1, wherein the amplifier means is an        injection locked laser amplifier.        16. The electro-optical system of claim 1, wherein a first part        of the composite beam is directed to a half waveplate that        rotates the polarization of the composite beam by 45 degrees and        then to a polarizing beam splitter that directs the resultant        interference patterns to a first and second camera with the        resulting measurements being used to compute an estimate of a        real part of a measured complex field of the return beacon beam.        17. The electro-optical system of claim 1, wherein a second part        of the composite beam is directed first to a quarter waveplate        with its crystal axis aligned to the polarization axis of the        minority reference beam and then to a half waveplate that        rotates the polarization of the composite beam by 45 degrees and        then to a polarizing beam splitter that directs the resultant        interference patterns to a third and fourth camera with the        resulting measurements being used to compute an estimate of an        imaginary part of a measured complex field of the return beacon        beam.        18. The electro-optical system of claim 1, wherein the minority        reference beam and the return beacon beam are at orthogonal        polarizations to one another.        19. The electro-optical system of claim 1, wherein the first and        second WFS consists of a π/3 waveplate, a 5/3πwaveplate, and a π        waveplate each associated with a separate camera and can be        aligned to the axis of polarization of the minority reference        beam.        20. (FIGS. 9,12) An electro-optical system for measurement of        aberrations induced on a laser beam by propagation through a        turbulent medium to a non-cooperative target, the system        comprising:    -   a) a mode locked beacon master oscillator that produces a        majority beacon beam comprising a high repetition rate (ranging        from about 100 to 100000 Hz) sequence of transform limited        pulsed laser beams and producing a minority reference beam that        has a repetition rate defined by the cavity length of the mode        locked beacon master oscillator (ranging typically from MHz to        GHz);    -   b) wherein a timing delay circuit receives the minority        reference beam and produces a delayed reference beam delayed to        coincide with an arrival time of a return beacon beam from a        target aimpoint along a propagation path axis;    -   c) wherein the majority beacon beam is transmitted through an        optical path through a telescope, and through the turbulent        medium to a target;    -   d) wherein the return beacon beam returns from the target        through the turbulent medium, telescope, optical path, and a        quarter waveplate in the optical path, then passes through a        first polarizing wave splitter optic; and    -   e) wherein the return beacon beam is then directed to a wave        front sensor (WFS) where it is combined with the minority        reference beam to form a composite beam for phase measurement.        21. The electro-optical system of claim 20, wherein a first part        of the composite beam is directed to a half waveplate that        rotates the polarization of the composite beam by 45 degrees and        then to a polarizing beam splitter that directs the resultant        interference patterns to a first and second camera with the        resulting measurements being used to compute an estimate of a        real part of a measured complex field of the return beacon beam.        22. The electro-optical system of claim 20, wherein a second        part of the composite beam is directed first to a quarter        waveplate with its crystal axis aligned to the polarization axis        of the minority reference beam and then to a half waveplate that        rotates the polarization of the composite beam by 45 degrees and        then to a polarizing beam splitter that directs the resultant        interference patterns to a third and fourth camera with the        resulting measurements being used to compute an estimate of an        imaginary part of a measured complex field of the return beacon        beam.        23. The electro-optical system of claim 20, wherein the minority        reference beam and the return beacon beam are at orthogonal        polarizations to one another.        24. The electro-optical system of claim 20, wherein the WFS        consists of a π/3 waveplate, a 5/3π waveplate, and a π waveplate        each associated with a separate camera and can be aligned to the        axis of polarization of the minority reference beam.        25. (FIGS. 1, 9, and 12, with an aspect of 8—the approach for        wavefront measurement with a non-cooperative target) An        electro-optical system for projection of laser beams through a        turbulent medium to a non-cooperative target, the system        comprising:    -   a) a master oscillator beam having an optical path to an        amplifier means;    -   b) said amplifier means forming a high energy laser (HEL) beam        to a target via an optical path;    -   c) said optical path including a steering mirror and a        telescope;    -   d) a mode locked beacon master oscillator that produces a        majority beacon beam comprising a high repetition rate (ranging        from about 100 to 100000 Hz) sequence of transform limited        pulsed laser beams and producing a minority reference beam that        has a repetition rate defined by the cavity length of the mode        locked beacon master oscillator (ranging typically from MHz to        GHz);    -   e) wherein a timing delay circuit receives the minority        reference beam and produces a delayed reference beam that is        delayed to coincide with an arrival of a return beacon beam from        a target aimpoint along a propagation path axis;    -   f) said majority beacon beam transmitted via an optical path to        a medium power amplifier which sends the majority beacon beam        via an optical path to the target;    -   g) wherein a return beacon beam comprising a high repetition        rate pulse train beam returns from the target through the        turbulent medium, telescope, optical path, and a quarter        waveplate in the optical path, then passes through a first        polarizing wave splitter optic;    -   h) wherein the return beacon beam is then directed to a first        beacon wave front sensor (WFS) where it is combined with the        minority reference beam to form a composite beam for phase        measurement;    -   i) said first WFS controlling a first phase correction and        steering device pair which (1) corrects the majority beacon beam        with respect to phase aberrations caused by propagation through        the turbulent medium and (2) provides phase commands to the        first phase correction and steering device pair that will result        in correction of amplitude aberrations in the beacon beam caused        by propagation through the turbulent medium;    -   j) a tracker and aim point controller which receives an image of        the target from an illumination source to generate a control        signal to control a steering mirror;    -   k) a third WFS receives a sample beam from the minority        reference beam after it passes through a spatial filter optic        and the fourth correction and steering device pair to compare to        a sample of the majority beacon beam after it passes through an        optical path including a propagation optics and the third        correction and steering device pair;    -   l) said third WFS also receives a HEL amplifier probe beam after        it passes through the amplifier means to interfere with a sample        probe beam from the HEL amplifier probe; and    -   m) said third WFS controlling a fourth correction and steering        device pair to correct for aberrations in the master oscillator        and amplifier means.        26. The system of claim 25, wherein the first and fourth pair of        phase correction and steering device pairs are optically        conjugate to one another.        27. The system of claim 25, wherein the return beacon beam is        formed as a cooperative beacon located at the target and pointed        toward the transmitting HEL optical path.        28. The system of claim 25, wherein the return beacon beam is        formed as an illuminator beam launched from an auxiliary        telescope to illuminate the target, and the reflection from the        target serves as the beacon beam.        29. The system of claim 25, wherein the return beacon beam is a        solar illumination of the target.        30. The system of claim 25, wherein the return beacon beam is a        thermal emission of the target.        31. The system of claim 25, wherein the amplifier means is        injection locked laser resonator.        32. The system of claim 25, wherein the image of the target is        formed as a cooperative beacon located at the target and pointed        toward the transmitting HEL optical path.        33. The system of claim 25, wherein the image of the target        received by the aim point controller is either a passive or        active illumination of the target.        34. The system of claim 25, wherein a sixth WFS receives a        beacon amplifier probe beam after it passes through a beacon        medium power amplifier and also receives a sample beam from the        beacon amplifier probe beam.        35. The system of claim 25, wherein the sixth WFS controls a        sixth correction and steering device pair.        36. The system of claim 25, wherein the amplifier means is a        high power laser amplifier.        37. The system of claim 25, wherein the amplifier means is an        injection locked laser amplifier.        38. The electro-optical system of claim 25, wherein a first part        of the composite beam is directed to a half waveplate that        rotates the polarization of the composite beam by 45 degrees and        then to a polarizing beam splitter that directs the resultant        interference patterns to a first and second camera with the        resulting measurements being used to compute an estimate of a        real part of a measured complex field of the return beacon beam.        39. The electro-optical system of claim 25, wherein a second        part of the composite beam is directed first to a quarter        waveplate with its crystal axis aligned to the polarization axis        of the minority reference beam and then to a half waveplate that        rotates the polarization of the composite beam by 45 degrees and        then to a polarizing beam splitter that directs the resultant        interference patterns to a third and fourth camera with the        resulting measurements being used to compute an estimate of an        imaginary part of a measured complex field of the return beacon        beam.        40. The electro-optical system of claim 25, wherein the minority        reference beam and the return beacon beam are at orthogonal        polarizations to one another.        41. The electro-optical system of claim 25, wherein the first        WFS consists of a π/3 waveplate, a 5/3π waveplate, and a π        waveplate each associated with a separate camera and can be        aligned to the axis of polarization of the minority reference        beam.        42. (FIG. 8) An electro-optical system for projection of laser        beams through a turbulent medium to a non-cooperative target,        the system comprising:    -   a) a master oscillator beam having an optical path to an        amplifier means;    -   b) said amplifier means forming a high energy laser (HEL) beam        to a target via an optical path;    -   c) said optical path including a steering mirror and a        telescope;    -   d) a mode locked beacon master oscillator that produces a        majority beacon beam comprising a high repetition rate (ranging        from about 100 to 100000 Hz) sequence of transform limited        pulsed laser beams and producing a minority reference beam that        has a repetition rate defined by the cavity length of the mode        locked beacon master oscillator (ranging typically from MHz to        GHz);    -   e) wherein a timing delay circuit receives the minority        reference beam and produces a delayed reference beam that is        delayed to coincide with the arrival of a return beacon beam        from a target aimpoint along a propagation path axis;    -   f) said majority beacon beam transmitted via an optical path to        a medium power amplifier which sends the majority beacon beam        via an optical path to the target;    -   g) wherein a return beacon beam comprising a high repetition        rate pulse train beam returns from the target through the        turbulent medium, telescope, optical path, and a quarter        waveplate in the optical path, then passes through a first        polarizing wave splitter optic;    -   h) wherein the return beacon beam is then directed to a first        beacon wave front sensor (WFS) where it is combined with the        minority reference beam to form a composite beam for phase        measurement;    -   i) said first WFS controlling a first phase correction and        steering device pair which corrects the majority beacon beam        with respect to phase aberrations caused by propagation through        the turbulent medium;    -   j) a tracker and aim point controller which receives an image of        the target from an illumination source, thereby generating a        control signal to control the steering mirror;    -   k) a third WFS (no second WFS is named) receives a sample beam        from the minority master oscillator beam after it passes through        a spatial filter optic and the fourth correction and steering        device pair to compare to a sample of the majority master        oscillator beam after it passes through an optical path        including a propagation optics and the third correction and        steering device pair;    -   l) said third WFS controlling a fourth correction and steering        device pair to correct for aberrations induced by propagation        through the third phase correction and steering device pair and        propagation optics;    -   m) a fifth WFS (no fourth WFS is named) receiving a HEL        amplifier probe beam after it passes through the amplifier        means; and    -   n) said fifth WFS controlling a fifth correction and steering        device pair.        43. The system of claim 42, wherein the first and fourth pair of        phase correction and steering device pairs are optically        conjugate to one another.        44. The system of claim 42, wherein the beam sampling optic is        highly transmissive at the beacon wavelength and receive        polarization, and is highly reflective at the beacon wavelength        and transmit polarization, and is highly reflective at the HEL        wavelength at both polarizations.        45. The system of claim 42, wherein the return beacon beam is        formed as a cooperative beacon located at the target and pointed        toward the transmitting HEL optical path.        46. The system of claim 42, wherein the return beacon beam is        formed as an illuminator beam launched from an auxiliary        telescope to illuminate the target, and the reflection from the        target serves as the beacon beam.        47. The system of claim 42, wherein the return beacon beam is a        solar illumination of the target.        48. The system of claim 42, wherein the return beacon beam is a        thermal emission of the target.        49. The system of claim 42, wherein the amplifier means is        replaced with an injection locked laser resonator.        50. The system of claim 42, wherein the image of the target is        formed as a cooperative beacon located at the target and pointed        toward the transmitting HEL optical path.        51. The system of claim 42, wherein the image of the target        received by the aim point controller is either a passive or        active illumination of the target.        52. The system of claim 42, wherein a sixth WFS receives a        beacon amplifier probe beam after it passes through a beacon        medium power amplifier and also receives a sample beam from the        beacon amplifier probe beam.        53. The system of claim 42, wherein the sixth WFS controls a        sixth correction and steering device pair.        54. The system of claim 42, wherein the amplifier means is a        high power laser amplifier.        55. The system of claim 42, wherein the amplifier means is an        injection locked laser amplifier.        56. The electro-optical system of claim 42, wherein a first part        of the composite beam is directed to a half waveplate that        rotates the polarization of the composite beam by 45 degrees and        then to a polarizing beam splitter that directs the resultant        interference patterns to a first and second camera with the        resulting measurements being used to compute an estimate of a        real part of a measured complex field of the return beacon beam.        57. The electro-optical system of claim 42, wherein a second        part of the composite beam is directed first to a quarter        waveplate with its crystal axis aligned to the polarization axis        of the minority reference beam and then to a half waveplate that        rotates the polarization of the composite beam by 45 degrees and        then to a polarizing beam splitter that directs the resultant        interference patterns to a third and fourth camera with the        resulting measurements being used to compute an estimate of an        imaginary part of a measured complex field of the return beacon        beam.        58. The electro-optical system of claim 42, wherein the minority        reference beam and the return beacon beam are at orthogonal        polarizations to one another.        59. The electro-optical system of claim 42, wherein the first        WFS consists of a π/3 waveplate, a 5/3π waveplate, and a π        waveplate each associated with a separate camera and can be        aligned to the axis of polarization of the minority reference        beam.        60. (FIG. 7) An electro-optical system for projection of laser        beams through a turbulent medium to a non-cooperative target,        the system comprising:    -   a) a master oscillator beam having an optical path to an        amplifier means;    -   b) said amplifier means forming a high energy laser (HEL) beam        to a target via an optical path;    -   c) said optical path including a steering mirror and a        telescope;    -   d) a mode locked beacon master oscillator that produces a        majority beacon beam comprising a high repetition rate (ranging        from about 100 to 100000 Hz) sequence of transform limited        pulsed laser beams and producing a minority reference beam that        has a repetition rate defined by the cavity length of the mode        locked beacon master oscillator (ranging typically from MHz to        GHz);    -   e) wherein a timing delay circuit receives the minority        reference beam and produces a delayed reference beam that is        delayed to coincide with the arrival of a return beacon beam        from a target aimpoint along a propagation path axis;    -   f) said majority beacon beam transmitted via an optical path to        a medium power amplifier which sends the majority beacon beam        via an optical path to the target;    -   g) wherein a return beacon beam comprising a high repetition        rate pulse train beam returns from the target through the        turbulent medium, telescope, optical path, and a quarter        waveplate in the optical path, then passes through a first        polarizing wave splitter optic;    -   h) wherein the return beacon beam is then directed to a first        beacon wave front sensor (WFS) where it is combined with the        minority reference beam to form a composite beam for phase        measurement;    -   i) said first WFS controlling a first phase correction and        steering device pair which (1) corrects the majority beacon beam        with respect to phase aberrations caused by propagation through        the turbulent medium and (2) provides phase commands to the        first phase correction and steering device pair that will result        in correction of amplitude aberrations in the beacon beam caused        by propagation through the turbulent medium;    -   j) a tracker and aim point controller which receives an image of        the target from an illumination source, thereby generating a        control signal to control the steering mirror;    -   k) a third WFS (no second WFS is named) receives a sample beam        from the minority master oscillator beam after it passes through        a spatial filter optic and the fourth correction and steering        device pair to compare to a sample of the majority master        oscillator beam after it passes through an optical path        including a propagation optics and the third correction and        steering device pair (no second correction and steering device        par is named);    -   l) said third WFS controlling a fourth correction and steering        device pair to correct for aberrations induced by propagation        through the third phase correction and steering device pair and        propagation optics;    -   m) a fifth WFS receiving a HEL amplifier probe beam after it        passes through the amplifier means; and    -   n) said fifth WFS controlling a fifth correction and steering        device pair.        61. The system of claim 60, wherein the first and fourth pair of        phase correction and steering device pairs are optically        conjugate to one another.        62. The system of claim 60, wherein the third pair of phase        correction and steering device pairs have a free space        propagation distance (from the conjugate plane of the first and        fourth phase correction and steering device pairs) of        approximately:        −D ² /λN    -   where D is the beam size, λ is the wavelength and N is the        number of phase correction device actuator spacings across the        beam.        63. The system of claim 60, wherein the beacon beam is formed as        a cooperative beacon located at the target and pointed toward        the transmitting HEL optical path.        64. The system of claim 60, wherein the beacon beam is formed as        an illuminator beam launched from an auxiliary telescope to        illuminate the target, and the reflection from the target serves        as the beacon beam.        65. The system of claim 60, wherein the beacon beam is a solar        illumination of the target.        66. The system of claim 60, wherein the beacon beam is a thermal        emission of the target.        67. The system of claim 60, wherein the amplifier means is an        injection locked laser resonator.        68. The system of claim 60, wherein the image of the target is        formed as a cooperative beacon located at the target and pointed        toward the transmitting HEL optical path.        69. The system of claim 60, wherein the image of the target        received by the aim point controller is either a passive or        active illumination of the target.        70. The system of claim 60, wherein a sixth WFS receives a        beacon amplifier probe beam after it passes through a beacon        medium power amplifier and also receives a sample beam from the        beacon amplifier probe beam.        71. The system of claim 70, wherein the sixth WFS controls a        sixth correction and steering device pair.        72. The system of claim 60, wherein the amplifier means is a        high power laser amplifier.        73. The system of claim 60, wherein the amplifier means is an        injection locked laser amplifier.        74. The electro-optical system of claim 60, wherein a first part        of the composite beam is directed to a half waveplate that        rotates the polarization of the composite beam by 45 degrees and        then to a polarizing beam splitter that directs the resultant        interference patterns to a first and second camera with the        resulting measurements being used to compute an estimate of a        real part of a measured complex field of the return beacon beam.        75. The electro-optical system of claim 60, wherein a second        part of the composite beam is directed first to a quarter        waveplate with its crystal axis aligned to the polarization axis        of the minority reference beam and then to a half waveplate that        rotates the polarization of the composite beam by 45 degrees and        then to a polarizing beam splitter that directs the resultant        interference patterns to a third and fourth camera with the        resulting measurements being used to compute an estimate of an        imaginary part of a measured complex field of the return beacon        beam.        76. The electro-optical system of claim 60, wherein the minority        reference beam and the return beacon beam are at orthogonal        polarizations to one another.        77. The electro-optical system of claim 60, wherein the first        and second WFS consists of a π/3 waveplate, a 5/3π waveplate,        and a π waveplate each associated with a separate camera and can        be aligned to the axis of polarization of the minority reference        beam.        78. (Variation of FIG. 8) An electro-optical system for        projection of laser beams through a turbulent medium to a        non-cooperative target, the system comprising:    -   a) a master oscillator beam having an optical path to an        amplifier means;    -   b) said amplifier means forming a high energy laser (HEL) beam        to a target via an optical path;    -   c) said optical path including a steering mirror and a        telescope;    -   d) a mode locked beacon master oscillator that produces a        majority beacon beam comprising a high repetition rate (ranging        from about 100 to 100000 Hz) sequence of transform limited        pulsed laser beams (a beacon beam) and producing a minority        reference beam that has a repetition rate defined by the cavity        length of the mode locked beacon master oscillator (ranging        typically from MHz to GHz);    -   e) wherein a timing delay circuit receives the minority        reference beam and produces a delayed reference beam that is        delayed to coincide with the arrival of a return beacon beam        from a target aimpoint along a propagation path axis;    -   f) said majority high repetition rate beacon beam transmitted        via an optical path to a medium power amplifier which sends the        majority beacon beam via an optical path to the target;    -   g) wherein a return beacon beam comprising a high repetition        rate pulse train beam returns from the target through the        turbulent medium, telescope, optical path, and a quarter        waveplate in the optical path, then passes through a first        polarizing wave splitter optic;    -   h) wherein the return beacon beam is then directed to a first        beacon wave front sensor (WFS) where it is combined with the        minority reference beam to form a composite beam for phase        measurement;    -   i) said first WFS controlling a first phase correction and        steering device pair which corrects the beacon beam with respect        to phase aberrations caused by propagation through the turbulent        medium;    -   j) a tracker and aim point controller which receives an image of        the target from an illumination source, thereby generating a        control signal to control the steering mirror;    -   k) a fifth WFS (no second, third or fourth WFS is named)        receiving a HEL amplifier probe beam after it passes through the        amplifier means; and    -   l) said fifth WFS controlling a fifth correction and steering        device pair (no second, third or fourth correction and steering        device pair is named).        79. The system of claim 78, wherein the beam sampling optic is        highly transmissive at the beacon wavelength and receive        polarization, and is highly reflective at the beacon wavelength        and transmit polarization, and is highly reflective at the HEL        wavelength at both polarizations.        80. The system of claim 78, wherein the return beacon beam is        formed as a cooperative beacon located at the target and pointed        toward the transmitting HEL optical path.        81. The system of claim 78, wherein the return beacon beam is        formed as an illuminator beam launched from an auxiliary        telescope to illuminate the target, and the reflection from the        target serves as the beacon beam.        82. The system of claim 78, wherein the return beacon beam is a        solar illumination of the target.        83. The system of claim 78, wherein the return beacon beam is a        thermal emission of the target.        84. The system of claim 78, wherein the amplifier means is an        injection locked laser resonator.        85. The system of claim 78, wherein the image of the target is        formed as a cooperative beacon located at the target and pointed        toward the transmitting HEL optical path.        86. The system of claim 78, wherein the image of the target        received by the aim point controller is either a passive or        active illumination of the target.        87. The system of claim 78, wherein a sixth WFS receives a        beacon amplifier probe beam after it passes through a beacon        medium power amplifier and also receives a sample beam from the        beacon amplifier probe beam.        88. The system of claim 87, wherein the sixth WFS controls a        sixth correction and steering device pair.        89. The system of claim 78, wherein the amplifier means is a        high power laser amplifier.        90. The system of claim 78, wherein the amplifier means is an        injection locked laser amplifier.        91. The electro-optical system of claim 78, wherein a first part        of the composite beam is directed to a half waveplate that        rotates the polarization of the composite beam by 45 degrees and        then to a polarizing beam splitter that directs the resultant        interference patterns to a first and second camera with the        resulting measurements being used to compute an estimate of the        real part of a measured field of the return beacon beam.        92. The electro-optical system of claim 78, wherein a second        part of the composite beam is directed first to a quarter        waveplate with its crystal axis aligned to the polarization axis        of the minority reference beam and then to a half waveplate that        rotates the polarization of the composite beam by 45 degrees and        then to a polarizing beam splitter that directs the resultant        interference patterns to a third and fourth camera with the        resulting measurements being used to compute an estimate of an        imaginary part of a measured complex field of the return beacon        beam.        93. The electro-optical system of claim 78, wherein the minority        reference beam and the return beacon beam are at orthogonal        polarizations to one another.

94. The electro-optical system of claim 78, wherein the first WFSconsists of a π/3 waveplate, a 5/3π waveplate, and a π waveplate eachassociated with a separate camera and can be aligned to the axis ofpolarization of the minority reference beam.

95. (Variation of FIGS. 6, 9, and 12) An electro-optical system forprojection of laser beams through a turbulent medium to anon-cooperative target, the system comprising:

-   -   a) a mode locked beacon master oscillator that produces a        majority beacon beam comprising a high repetition rate (ranging        from about 100 to 100000 Hz) sequence of transform limited        pulsed laser beams and producing a minority reference beam that        has a repetition rate defined by the cavity length of the mode        locked beacon master oscillator (ranging typically from MHz to        GHz);    -   b) said majority beacon beam having an optical path to an        amplifier means;    -   c) said amplifier means forming a high energy laser (HEL) beam        to a target via an optical path;    -   d) said optical path including a steering mirror and a        telescope;    -   e) wherein a timing delay circuit receives the minority        reference beam and produces a delayed reference beam that is        delayed to coincide with the arrival of a return beacon beam        from a target aimpoint along a propagation path axis;    -   f) said majority high repetition rate beacon beam transmitted        via an optical path to a medium power amplifier which sends the        beacon beam via an optical path to the target;    -   g) wherein a return beacon beam comprising a high repetition        rate pulse train beam returns from the target through the        turbulent medium, telescope, optical path, and a quarter        waveplate in the optical path, then passes through a first        polarizing wave splitter optic;    -   h) wherein the high repetition rate return beacon beam is then        directed to a first beacon wave front sensor (WFS) where it is        combined with the minority reference beam to form a composite        beam for phase measurement;    -   i) said first WFS controlling a first phase correction and        steering device pair which (1) corrects the beacon beam with        respect to phase aberrations caused by propagation through the        turbulent medium and (2) provides phase commands to the first        phase correction and steering device pair that will result in        correction of amplitude aberrations in the beacon beam caused by        propagation through the turbulent medium;    -   j) a tracker and aim point controller which receives an image of        the target from an illumination source, thereby generating a        control signal to control the steering mirror;    -   k) said minority reference beam further comprising a sample        which goes to a second beacon WFS which also receives a sample        of the returning beacon beam after said returning beacon beam        passes through a further propagation optics and a third and        second correction and steering device pair;    -   l) said second beacon WFS controlling a third correction and        steering device pair which corrects for remaining aberrations in        the return beacon beam, resulting in correction of both        amplitude and phase aberrations caused by propagation through        the turbulent medium;    -   m) a third WFS receives a sample beam from the minority mode        locked beacon master oscillator beam after it passes through a        spatial filter optic and the fourth correction and steering        device pair to compare to a sample of the majority mode locked        beacon master oscillator beam after it passes through an optical        path including a propagation optics and the third correction and        steering device pair;    -   n) said third WFS controlling a fourth correction and steering        device pair to correct for aberrations induced by propagation        through the third phase correction and steering device pair and        propagation optics;    -   o) a fourth WFS receiving a sample of the majority mode locked        beacon master oscillator beam and a minority mode locked beacon        master oscillator beam after it passes through a spatial filter        optic and the second correction and steering device pair;    -   p) said fourth WFS controlling a second phase correction and        steering device pair to correct for aberrations in the master        oscillator;    -   q) a fifth WFS receiving an amplifier probe beam after it passes        through the amplifier means; and    -   r) said fifth WFS controlling a fifth correction and steering        device pair.        96. The system of claim 95, wherein the first and fourth pair of        phase correction and steering device pairs are optically        conjugate to one another.        97. The system of claim 95, wherein the second and third pair of        phase correction and steering device pairs are optically        conjugate to one another.        98. The system of claim 95, wherein the second and third pair of        phase correction and steering device pairs have a free space        propagation distance (from the conjugate plane of the first and        fourth phase correction and steering device pairs) of        approximately:        −D ² /λN    -   where D is the beam size, X is the wavelength and N is the        number of phase correction device actuator spacings across the        beam.        99. The system of claim 95, wherein the image of the target is        formed as a cooperative beacon located at the target and pointed        toward the transmitting HEL optical path.        100. The system of claim 95, wherein the image of the target        received by the aim point controller is either a passive or        active illumination of the target.        101. The system of claim 95, wherein the amplifier means is a        high power laser amplifier.        102. The system of claim 95, wherein the amplifier means is an        injection locked laser amplifier.        103. The electro-optical system of claim 95, wherein a first        part of the composite beam is directed to a half waveplate that        rotates the polarization of the composite beam by 45 degrees and        then to a polarizing beam splitter that directs the resultant        interference patterns to a first and second camera with the        resulting measurements being used to compute an estimate of a        real part of a measured complex field of the return beacon beam.        104. The electro-optical system of claim 95, wherein a second        part of the composite beam is directed first to a quarter        waveplate with its crystal axis aligned to the polarization axis        of the minority reference beam and then to a half waveplate that        rotates the polarization of the composite beam by 45 degrees and        then to a polarizing beam splitter that directs the resultant        interference patterns to a third and fourth camera with the        resulting measurements being used to compute an estimate of an        imaginary part of a measured complex field of the return beacon        beam.        105. The electro-optical system of claim 95, wherein the        minority reference beam and the return beacon beam are at        orthogonal polarizations to one another.        106. The electro-optical system of claim 95, wherein the first        and second WFS consists of a π/3 waveplate, a 5/3π waveplate,        and a π waveplate each associated with a separate camera and can        be aligned to the axis of polarization of the minority reference        beam.        107. (Variation of FIGS. 1, 9, and 12, with an aspect of 8—the        approach for wavefront measurement with a non-cooperative        target) An electro-optical system for projection of laser beams        through a turbulent medium to a non-cooperative target, the        system comprising:    -   a) a mode locked beacon master oscillator that produces a        majority beacon beam comprising a high repetition rate (ranging        from about 100 to 100000 Hz) sequence of transform limited        pulsed laser beams (a beacon beam) and producing a minority        reference beam that has a repetition rate defined by the cavity        length of the mode locked beacon master oscillator (ranging        typically from MHz to GHz);    -   b) said majority beacon beam having an optical path to an        amplifier means;    -   c) said amplifier means forming a high energy laser (HEL) beam        to a target via an optical path;    -   d) said optical path including a steering mirror and a        telescope;    -   e) wherein a timing delay circuit receives the minority        reference beam and produces a delayed reference beam that is        delayed to coincide with an arrival of a return beacon beam from        a target aimpoint along a propagation path axis;    -   f) said majority beacon beam transmitted via an optical path to        a medium power amplifier which sends the majority beacon beam        via an optical path to the target;    -   g) wherein a return beacon beam comprising a high repetition        rate pulse train beam returns from the target through the        turbulent medium, telescope, optical path, and a quarter        waveplate in the optical path, then passes through a first        polarizing wave splitter optic;    -   h) wherein the return beacon beam is then directed to a first        beacon wave front sensor (WFS) where it is combined with the        minority reference beam to form a composite beam for phase        measurement;    -   i) said first WFS controlling a first phase correction and        steering device pair which (1) corrects the beacon beam with        respect to phase aberrations caused by propagation through the        turbulent medium and (2) provides phase commands to the first        phase correction and steering device pair that will result in        correction of amplitude aberrations in the beacon beam caused by        propagation through the turbulent medium;    -   j) a tracker and aim point controller which receives an image of        the target from an illumination source to generate a control        signal to control a steering mirror;    -   k) a third WFS receives a sample beam from the minority mode        locked beacon master oscillator beam after it passes through a        spatial filter optic and the fourth correction and steering        device pair to compare to a sample of the majority mode locked        beacon master oscillator beam after it passes through an optical        path including a propagation optics and the third correction and        steering device pair;    -   l) said third WFS also receives a HEL amplifier probe beam after        it passes through the amplifier means to interfere with a sample        probe beam from the HEL amplifier probe; and    -   m) said third WFS controlling a fourth correction and steering        device pair to correct for aberrations in the mode locked beacon        master oscillator beam and high power amplifier.        108. The system of claim 107, wherein the first and fourth pair        of phase correction and steering device pairs are optically        conjugate to one another.        109. The system of claim 107, wherein the image of the target is        formed as a cooperative beacon located at the target and pointed        toward the transmitting HEL optical path.        110. The system of claim 107, wherein the image of the target        received by the aim point controller is either a passive or        active illumination of the target. 6111. The system of claim        107, wherein the amplifier means is a high power laser        amplifier.        112. The system of claim 107, wherein the amplifier means is an        injection locked laser amplifier.        113. The electro-optical system of claim 107, wherein a first        part of the composite beam is directed to a half waveplate that        rotates the polarization of the composite beam by 45 degrees and        then to a polarizing beam splitter that directs the resultant        interference patterns to a first and second camera with the        resulting measurements being used to compute an estimate of a        real part of a measured complex field of the return beacon beam.        114. The electro-optical system of claim 107, wherein a second        part of the composite beam is directed first to a quarter        waveplate with its crystal axis aligned to the polarization axis        of the minority reference beam and then to a half waveplate that        rotates the polarization of the composite beam by 45 degrees and        then to a polarizing beam splitter that directs the resultant        interference patterns to a third and fourth camera with the        resulting measurements being used to compute an estimate of an        imaginary part of a measured complex field of the return beacon        beam.        115. The electro-optical system of claim 107, wherein the        minority reference beam and the return beacon beam are at        orthogonal polarizations to one another.        116. The electro-optical system of claim 107, wherein the fist        WFS consists of a π/3 waveplate, a 5/3π waveplate, and a π        waveplate each associated with a separate camera and can be        aligned to the axis of polarization of the minority reference        beam.        117. (Variation of FIG. 8) An electro-optical system for        projection of laser beams through a turbulent medium to a        non-cooperative target, the system comprising:    -   a) a mode locked beacon master oscillator that produces a        majority high repetition rate (ranging from about 100 to 100000        Hz) sequence of transform limited pulsed laser beams (a beacon        beam) and a minority reference beam that has a repetition rate        defined by the cavity length of the mode locked beacon master        oscillator (ranging typically from MHz to GHz);    -   b) said mode locked beacon master oscillator beam having an        optical path to an amplifier means;    -   c) said amplifier means forming a high energy laser (HEL) beam        to a target via an optical path;    -   d) said optical path including a steering mirror and a        telescope;    -   e) wherein a timing delay circuit receives the minority        reference beam and produces a delayed reference beam that is        delayed to coincide with the arrival of a return beacon beam        from a target aimpoint along a propagation path axis;    -   f) said majority high repetition rate beacon beam transmitted        via an optical path to a medium power amplifier which sends the        beacon beam via an optical path to the target;    -   g) wherein the high repetition rate return beacon pulse train        beam returns from the target through the turbulent medium,        telescope, optical path, and a quarter waveplate in the optical        path, then passes through a first polarizing wave splitter        optic;    -   h) wherein the return beacon beam is then directed to a first        beacon wave front sensor (WFS) where it is combined with the        minority reference beam to form a composite beam for phase        measurement;    -   i) said first WFS controlling a first phase correction and        steering device pair which corrects the beacon beam with respect        to phase aberrations caused by propagation through the turbulent        medium;    -   j) a tracker and aim point controller which receives an image of        the target from an illumination source, thereby generating a        control signal to control the steering mirror;    -   k) a third WFS (no second WFS is named) receives a sample beam        from the minority mode locked beacon master oscillator beam        after it passes through a spatial filter optic and the fourth        correction and steering device pair to compare to a sample of        the majority mode locked beacon master oscillator beam after it        passes through an optical path including a propagation optics        and the third correction and steering device pair;    -   l) said third WFS controlling a fourth correction and steering        device pair to correct for aberrations induced by propagation        through the third phase correction and steering device pair and        propagation optics;    -   m) a fifth WFS (no fourth WFS is named) receiving a HEL        amplifier probe beam after it passes through the amplifier        means; and    -   n) said fifth WFS controlling a fifth correction and steering        device pair.        118. The system of claim 117, wherein the first and fourth pair        of phase correction and steering device pairs are optically        conjugate to one another.        119. The system of claim 117, wherein the beam sampling optic is        highly transmissive at the beacon wavelength and receive        polarization, and is highly reflective at the beacon wavelength        and transmit polarization, and is highly reflective at the HEL        wavelength at both polarizations.        120. The system of claim 117, wherein the image of the target is        formed as a cooperative beacon located at the target and pointed        toward the transmitting HEL optical path.        121. The system of claim 117, wherein the image of the target        received by the aim point controller is either a passive or        active illumination of the target.        122. The system of claim 117, wherein the amplifier means is a        high power laser amplifier.        123. The system of claim 117, wherein the amplifier means is an        injection locked laser amplifier.        124. The electro-optical system of claim 117, wherein a first        part of the composite beam is directed to a half waveplate that        rotates the polarization of the composite beam by 45 degrees and        then to a polarizing beam splitter that directs the resultant        interference patterns to a first and second camera with the        resulting measurements being used to compute an estimate of a        real part of a measured complex field of the return beacon beam.        125. The electro-optical system of claim 117, wherein a second        part of the composite beam is directed first to a quarter        waveplate with its crystal axis aligned to the polarization axis        of the minority reference beam and then to a half waveplate that        rotates the polarization of the composite beam by 45 degrees and        then to a polarizing beam splitter that directs the resultant        interference patterns to a third and fourth camera with the        resulting measurements being used to compute an estimate of an        imaginary part of a measured complex field of the return beacon        beam.        126. The electro-optical system of claim 117, wherein the        minority reference beam and the return beacon beam are at        orthogonal polarizations to one another.        127. The electro-optical system of claim 117, wherein the first        WFS consists of a π/3 waveplate, a 5/3π waveplate, and a π        waveplate each associated with a separate camera and can be        aligned to the axis of polarization of the minority reference        beam.        128. (Variation of FIG. 7) An electro-optical system for        projection of laser beams through a turbulent medium to a        non-cooperative target, the system comprising:    -   a) a mode locked beacon master oscillator that produces a        majority beacon beam comprising a high repetition rate (ranging        from about 100 to 100000 Hz) sequence of transform limited        pulsed laser beams (a beacon beam) and producing a minority        reference beam that has a repetition rate defined by the cavity        length of the mode locked beacon master oscillator (ranging        typically from MHz to GHz);    -   b) said mode locked beacon master oscillator beam having an        optical path to an amplifier means;    -   c) said amplifier means forming a high energy laser (HEL) beam        to a target via an optical path;    -   d) said optical path including a steering mirror and a        telescope;    -   e) wherein a timing delay circuit receives the minority        reference beam and produces a delayed reference beam that is        delayed to coincide with the arrival of a return beacon beam        from a target aimpoint along a propagation path axis;    -   f) said majority beacon beam transmitted via an optical path to        a medium power amplifier which sends the majority beacon beam        via an optical path to the target;    -   g) wherein a return beacon beam comprising a high repetition        rate pulse train beam returns from the target through the        turbulent medium, telescope, optical path, and a quarter        waveplate in the optical path, then passes through a first        polarizing wave splitter optic;    -   h) wherein the return beacon beam is then directed to a first        beacon wave front sensor (WFS) where it is combined with the        minority reference beam to form a composite beam for phase        measurement;    -   i) said first WFS controlling a first phase correction and        steering device pair which (1) corrects the beacon beam with        respect to phase aberrations caused by propagation through the        turbulent medium and (2) provides phase commands to the first        phase correction and steering device pair that will result in        correction of amplitude aberrations in the beacon beam caused by        propagation through the turbulent medium;    -   j) a tracker and aim point controller which receives an image of        the target from an illumination source, thereby generating a        control signal to control the steering mirror;    -   k) a third WFS (no second WFS is named) receives a sample beam        from the minority reference beam after it passes through a        spatial filter optic and the fourth correction and steering        device pair to compare to a sample of the majority beacon beam        after it passes through an optical path including a propagation        optics and the third correction and steering device pair (no        second correction and steering device par is named);    -   l) said third WFS controlling a fourth correction and steering        device pair to correct for aberrations induced by propagation        through the third phase correction and steering device pair and        propagation optics;    -   m) a fifth WFS receiving a HEL amplifier probe beam after it        passes through the amplifier means; and    -   n) said fifth WFS controlling a fifth correction and steering        device pair.        129. The system of claim 128, wherein the first and fourth pair        of phase correction and steering device pairs are optically        conjugate to one another.        130. The system of claim 128, wherein the third pair of phase        correction and steering device pairs have a free space        propagation distance (from the conjugate plane of the first and        fourth phase correction and steering device pairs) of        approximately:        −D ² /λN    -   where D is the beam size, X is the wavelength and N is the        number of phase correction device actuator spacings across the        beam.        131. The system of claim 128, wherein the image of the target is        formed as a cooperative beacon located at the target and pointed        toward the transmitting HEL optical path.        132. The system of claim 128, wherein the image of the target        received by the aim point controller is either a passive or        active illumination of the target.        133. The system of claim 128, wherein the amplifier means is a        high power laser amplifier.        134. The system of claim 130, wherein the amplifier means is an        injection locked laser amplifier.        135. The electro-optical system of claim 128, wherein a first        part of the composite beam is directed to a half waveplate that        rotates the polarization of the composite beam by 45 degrees and        then to a polarizing beam splitter that directs the resultant        interference patterns to a first and second camera with the        resulting measurements being used to compute an estimate of a        real part of a measured complex field of the return beacon beam.        136. The electro-optical system of claim 128, wherein a second        part of the composite beam is directed first to a quarter        waveplate with its crystal axis aligned to the polarization axis        of the minority reference beam and then to a half waveplate that        rotates the polarization of the composite beam by 45 degrees and        then to a polarizing beam splitter that directs the resultant        interference patterns to a third and fourth camera with the        resulting measurements being used to compute an estimate of an        imaginary part of a measured complex field of the return beacon        beam.        137. The electro-optical system of claim 1280, wherein the        minority reference beam and the return beacon beam are at        orthogonal polarizations to one another.        138. The electro-optical system of claim 128, wherein the first        and second WFS consists of a π/3 waveplate, a 5/3π waveplate,        and a π waveplate each associated with a separate camera and can        be aligned to the axis of polarization of the minority reference        beam.        139. (Variation of FIG. 8) An electro-optical system for        projection of laser beams through a turbulent medium to a        non-cooperative target, the system comprising:    -   a) a mode locked beacon master oscillator that produces a        majority beacon beam comprising a high repetition rate (ranging        from about 100 to 100000 Hz) sequence of transform limited        pulsed laser beams and producing a minority reference beam that        has a repetition rate defined by the cavity length of the mode        locked beacon master oscillator (ranging typically from MHz to        GHz);    -   b) said mode locked beacon master oscillator beam having an        optical path to an amplifier means;    -   c) said amplifier means forming a high energy laser (HEL) beam        to a target via an optical path;    -   d) said optical path including a steering mirror and a        telescope;    -   e) wherein a timing delay circuit receives the minority        reference beam and produces a delayed reference beam that is        delayed to coincide with the arrival of a return beacon beam        from a target aimpoint along a propagation path axis;    -   f) said majority beacon beam transmitted via an optical path to        a medium power amplifier which sends the majority beacon beam        via an optical path to the target;    -   g) wherein a return beacon a beam comprising a high repetition        rate pulse train beam returns from the target through the        turbulent medium, telescope, optical path, and a quarter        waveplate in the optical path, then passes through a first        polarizing wave splitter optic;    -   h) wherein the return beacon beam is then directed to a first        beacon wave front sensor (WFS) where it is combined with the        minority reference beam to form a composite beam for phase        measurement;    -   i) said first WFS controlling a first phase correction and        steering device pair which corrects the majority beacon beam        with respect to phase aberrations caused by propagation through        the turbulent medium;    -   j) a tracker and aim point controller which receives an image of        the target from an illumination source, thereby generating a        control signal to control the steering mirror;    -   k) a fifth WFS (no second, third or fourth WFS is named)        receiving a HEL amplifier probe beam after it passes through the        amplifier means; and    -   l) said fifth WFS controlling a fifth correction and steering        device pair (no second, third or fourth correction and steering        device pair is named).        140. The system of claim 139, wherein the beam sampling optic is        highly transmissive at the beacon wavelength and receive        polarization, and is highly reflective at the beacon wavelength        and transmit polarization, and is highly reflective at the HEL        wavelength at both polarizations.        141. The system of claim 139, wherein the image of the target is        formed as a cooperative beacon located at the target and pointed        toward the transmitting HEL optical path.        142. The system of claim 139, wherein the image of the target        received by the aim point controller is either a passive or        active illumination of the target.        143. The system of claim 139, wherein the amplifier means is a        high power laser amplifier.        144. The system of claim 139, wherein the amplifier means is an        injection locked laser amplifier.        145. The electro-optical system of claim 139, wherein a first        part of the composite beam is directed to a half waveplate that        rotates the polarization of the composite beam by 45 degrees and        then to a polarizing beam splitter that directs the resultant        interference patterns to a first and second camera with the        resulting measurements being used to compute an estimate of a        real part of a measured complex field of the return beacon beam.        146. The electro-optical system of claim 139, wherein a second        part of the composite beam is directed first to a quarter        waveplate with its crystal axis aligned to the polarization axis        of the minority reference beam and then to a half waveplate that        rotates the polarization of the composite beam by 45 degrees and        then to a polarizing beam splitter that directs the resultant        interference patterns to a third and fourth camera with the        resulting measurements being used to compute an estimate of an        imaginary part of a measured complex field of the return beacon        beam.        147. The electro-optical system of claim 139, wherein the        minority reference beam and the return beacon beam are at        orthogonal polarizations to one another.        148. The electro-optical system of claim 139, wherein the first        WFS consists of a π/3 waveplate, a 5/3π waveplate, and a π        waveplate each associated with a separate camera and can be        aligned to the axis of polarization of the minority reference        beam.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustrating the principle of pre-compensation ofphase aberrations both in a laser amplifier and due to turbulence;including correction of aberrations in the master oscillator beam.

FIG. 2. is a second alternate embodiment schematic of the presentinvention illustrating the principle of pre-compensation of phaseaberrations both in a laser amplifier and due to turbulence; includingcorrection of aberrations in the master oscillator beam.

FIG. 3 is a third alternate schematic of the present inventionillustrating the principle of pre-compensation of phase aberrations bothin a laser amplifier and due to turbulence; excluding correction ofaberrations in the master oscillator beam.

FIG. 4 is a fourth alternate embodiment schematic of the presentinvention illustrating the principle of pre-compensation of phase andamplitude aberrations both in a laser amplifier and due to turbulence;including correction of aberrations in the master oscillator beam.

FIG. 5 is a schematic of the present invention illustrating theprinciple of pre-compensation of phase and amplitude aberrations both ina laser amplifier and due to turbulence; excluding correction ofaberrations in the master oscillator beam.

FIG. 6 is a schematic of the present invention illustrating theprinciple of pre-compensation of phase and amplitude aberrations both ina laser amplifier and due to turbulence; ‘including’ correction ofaberrations in the master oscillator beam and including a preferredembodiment for use with non-cooperative targets and continuous wave orpulsed high energy laser beams where the beacon laser master oscillatoris a mode locked short pulse laser and is amplified in a separate beampath.

FIG. 7 is a schematic of the present invention illustrating theprinciple of pre-compensation of phase and amplitude aberrations both ina laser amplifier and due to turbulence; ‘excluding’ correction ofaberrations in the master oscillator beam and including a preferredembodiment for use with non-cooperative targets and continuous wave orpulsed high energy laser beams where the beacon laser master oscillatoris a mode locked short pulse laser and is amplified in a separate beampath.

FIG. 8 is a schematic of the present invention illustrating theprinciple of pre-compensation of phase aberrations both in a laseramplifier and due to turbulence; including correction of aberrations inthe master oscillator beam and including a preferred embodiment for usewith non-cooperative targets and continuous wave or pulsed high energylaser beams where the beacon laser master oscillator is a mode lockedshort pulse laser and is amplified in a separate beam path.

FIG. 9A is a drawing illustrating the principle of Broadband CoherentAdaptive Optics (BCAO), of which Target Feature Adaptive Optics (TFAO)is a special case, using a mode locked master oscillator seed laserwhich has transform limited pulses.

FIG. 9B is a schematic representing the drawing of FIG. 9A andillustrating the principle of Broadband Coherent Adaptive Optics (BCAO),of which Target Feature Adaptive Optics (TFAO) is a special case, usinga mode locked master oscillator seed laser which has transform limitedpulses.

FIG. 10 is a schematic for the wavefront sensor optics for the method ofTFAO or BCAO defined in FIG. 9.

FIG. 11 is a schematic for an alternate sub-optimal implementation ofwavefront sensor optics for the method of TFAO or BCAO defined in FIG.6. The reference and return pulse are at orthogonal polarizations.

FIG. 12 is a schematic of the preferred implementation for the wavefrontsensor optics for the method of TFAO or BCAO defined in FIG. 6. Thereference and return pulse are at orthogonal polarizations and thediagram here forms a 4-bin spatial phase shifting interferometer.

FIG. 13 is a chart showing beam profile and cumulative power in thebucket as a function of bucket diameter and a refractive index.

Before explaining the disclosed embodiment of the present invention indetail, it is to be understood that the invention is not limited in itsapplication to the details of the particular arrangement shown, sincethe invention is capable of other embodiments. Also, the terminologyused herein is for the purpose of description and not of limitation.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram schematic illustrating the principle ofpre-compensation of phase aberrations both in a laser amplifier and dueto turbulence; including correction of aberrations in the masteroscillator beam. FIG. 1 is shown by way of example and not oflimitation. There are alternate means of displaying the laser path(s) asthose skilled in the art would recognize. The most straightforward formof the Integrated Laser Field Conjugation System (ILFCS) is illustratedin FIG. 1. The system consists of a low power master oscillator 100 withmaster oscillator beam 100B where low power is defined as “low enough tobe compensated using the phase correction device selected”. The masteroscillator beam or high energy laser beam 100B is directed to beamsplitter 102 that is highly reflective at the wavelength of the masteroscillator. Beam splitter 102 divides the master oscillator beam 100Binto high energy laser (HEL) seed beam 100S, and HEL reference beam100R. The majority of the master oscillator beam, HEL seed beam 100S isdirected via mirror M1 through the probe aperture sharing element 122(which those skilled in the art will recognize should normally be areflective aperture sharing element despite being shown here astransmissive at the HEL seed beam wavelength) and through the phasecorrection device and fine steering mirror ‘pair 1’ 110 (generically thephase correction device is labeled as a DM or deformable mirror herewhile the fine steering mirror is generically labeled as a FSM butneither are restricted to being reflective phase correction/steeringdevices). HEL reference beam 100R is spatially filtered via the spatialfilter optics 145. The spatial filter optics can be one of any number ofmethods known to those skilled in the art, including use of a singlemode fiber or pinhole filter. The HEL reference beam 100R is thendirected through the phase correction device and fine steering mirror‘pair 2’ 115 and to the highly reflective beam splitter 103 (at themaster oscillator wavelength). An interference pattern 100RS of the twomaster oscillator beam samples is formed that is relayed to the masteroscillator (MO) wavefront sensor (WFS) 120. The majority sample of themaster oscillator beam HEL reference beam 100S, after passing throughthe phase correction device and FSM ‘pair 1’ 110 system is directed bythe Beacon Aperture Sharing Element 2 (ASE2) 125 through a high powerlaser amplifier 150 (or is used to injection seed a high power laserresonator). The Beacon ASE2 125 is designed to be highly transmissivefor the return beacon beam 105B and highly reflective for the HEL seedbeam 100S. Selection and design of the Beacon ASE is well understood forthose skilled in the art.

The nominal form for the laser resonator could be either a single ormulti-pass amplifier or it could be an unstable laser resonator. In thelatter case this laser resonator would nominally be configured as eitheran amplifier (where multi-pass gain is effected from design of theunstable resonator geometry) or as a classical injection locked ringlaser resonator. The laser amplifier 150 (or resonator), regardless,must have sufficient field of view to enable pre-compensation for theaberrations in turbulence that will be carried on the beam through thelaser amplifier or resonator. The resultant high power beam 100RS afteramplification reflects off of the Probe ASE 154 and an additional BeaconASE1 152 (where the Beacon ASE2 125 is identical or very similar innature to the Beacon ASE1 152). The Probe ASE 154 is designed to behighly reflective at the HEL wavelength and sufficiently transmissive atthe Probe Beam 165 wavelength. Next, the high power beam 100RS isdirected through a common path steering device (SM) 160 (nominallylabeled SM for steering mirror but this could include both a coarse andfine steering mirror and is not restricted to being a reflective mirrordevice) and then to the telescope 170 (or beam director) which focusesthe beam through turbulence (turbulent medium) 180 to target 190. Areturn beacon beam 105B is used to measure the aberrations in theturbulent medium 180 and telescope 170 and overall optical beam path.Return beacon beam 105B may be reflected from a non-cooperative targetor it can be from a generated source beacon 105 at the target. By meansof an unspecified method, a return beacon beam 105B from the target 190propagates through turbulence 180 and the telescope or beam director 170and common path SM 160. The return beacon beam 105B then passes throughbeacon ASE1 152 and then is relayed using standard methods through relayoptics 140 and mirror M5 and through beacon ASE2 125. Return beacon beam105B then is directed through first the phase correction device andDM1/FSM1 pair 110 and then through the phase correction device andDM2/FSM2 pair 115 and into the Beacon WFS 124.

The majority sample of the probe beam 165M of a probe beam 165 isinjected at Probe ‘ASE 1’ 154 and passes through the laser amplifier150. This probe beam is used to measure the aberrations in the lasergain medium. This sample of the probe beam is directed around the phasecorrection device and DM1/FSM1 pair 110 using Probe ‘ASE 2’ 122 andProbe ‘ASE 3’ 123 and through the beam splitter 103 between the phasecorrection device and FSM pairs.

The minority sample probe reference beam 165S of probe beam 165 thatreflects from Probe ‘ASE 1’ 154 is directed for injection co-linear tothe master oscillator reference beam to form the probe reference beam165S at the probe injection element 127. Probe reference beam 165S isthen directed through the phase correction device and DM2/FSM2 pair 115and then reflects off of beam splitter 103 between the phase correctiondevice and FSM pairs and the resultant interference pattern is directedto the MO and Probe WFS 120.

Finally, along the beacon beam path, an imaging beam path at anadditional suitable wavelength to generate imagery of the target 190 isincluded. The imaging beam 106B is generated using either passive oractive illumination of the target. If a point source beacon isavailable, then the imaging beam can be a sample of the beacon beam. Theimaging beam path is noted to include correction by all correctiondevices in the beam path. The imaging beam path is directed into animaging camera or cameras (within the tracker and aimpoint control 107)that can be used by standard methods for control of tracking and theaimpoint 107. Tracker and aimpoint control 107 adjusts steering mirror160 via controls CCFSM for target tracking.

The discussion above focused only on description of the optical beampaths, but did not describe how the phase correction devices andsteering devices are controlled. The details of the control systems arenot critical for implementation of the ILFCS and are described brieflybelow.

The imaging beam path signal 106B is used to control the common pathsteering device (SM 160). Any number of standard tracking and pointingalgorithms for object tracking and pointing can be used, including butnot limited to offset centroid tracking, offset thresholded centroidtracking, offset leading edge tracking, etc.

Next, the beacon wavefront sensor signal is used to control phasecorrection device (DM1 110) via control signal CC1. A very lowbandwidth, leaky integrator control loop from this sensor to control thesteering device (FSM1 110) may be used if necessary to compensate forslow rate non-common path drift. It should be noted that the correctionapplied to phase correction device 110 inherently includes commands thatwill attempt to correct not only for the measured aberrations in theturbulent beam path 180, but also aberrations present on the phasecorrection device DM2 115. This is illustrated by the following:

-   -   1. Measurements on beacon path WFS are e_(B)=φ_(A)+c₁+c₂, where        φ_(A) is the aberration induced by propagation through        turbulence 180 and the telescope 170, c₁ is the correction        applied by the phase correction device 110, and c₂ is the        correction applied by the phase correction device 115.    -   2. As a result, the command that nulls the error, e_(B), is        c₁=−φ_(A)−c₂.

The probe and HEL interference fringe patterns are used to control phasecorrection device (DM2) and steering device (FSM 2) pair 115 via controlsignals CC2. Because the phase correction and steering device pair 115are only applied to the probe and HEL reference devices, the appropriatecontrol commands generated for compensation are not the opposite of themeasured aberrations in the HEL master oscillator 100 and probe beams,but instead match the aberrations in the HEL master oscillator beam 100Band probe beam 165. This is illustrated by the following:

-   -   1. Measurements on the MO and probe WFS 120 are respectively        e_(H)=H φ_(H)−c₂, and e_(P)=φ_(L)−c₂, where φ_(H) is the        aberration on the HEL master oscillator beam and φ_(L) is        aberration in the laser amplifier beam path.    -   2. The command that nulls the signal e_(H)+e_(P) is        c₂=φ_(H)+φ_(L).

In so doing, we note at this point that a copy of the aberrations in thelaser resonator is introduced into the signal observed by the beaconbeam path WFS.

Due to the fact already noted that the beacon path WFS 124 then observesthe aberrations on the phase correction device 115, we note that theresultant command applied to phase correction device 1 110 is given by;c ₁=−φ_(A)−φ_(H)−φ_(L)

-   -   (The command that nulls the error, e_(B))

This exact command provides compensation for both aberrations in theinjected high energy laser master oscillator 100, the laser gain medium,and for propagation through turbulence 180—precisely the desired result.This command is applied to a correction device in the low power beampath.

The remaining control paths to be noted are control of the steeringdevices FSM1 110 and FSM2 115. We have already noted an optional lowbandwidth leaky integral control path for the steering device FSM1 110from the beacon path WFS. The low bandwidth correction applied to FSM2115 is the tilt signal from the interference patterns observed on the MOand Probe WFS 120. In addition the opposite of this same signal isapplied to FSM1 110. This ensures that pre-compensation for tilt in thelaser amplifier 150 is included, but pre-compensation for turbulenceinduced aberrations is confined to correction by the steering mirror, SM160 after the laser amplifier 150. This method will avoid loss of fieldof view and reduction in laser amplification efficiency due toattempting to correct for turbulence induced tilt aberrations prior tothe amplifier.

At this point, we can note for the imaging path, due to the fact thatthe imaging sensor is corrected by all of the correction devices, thelaser and master oscillator aberrations on the correction devices cancelone another, leaving a beam path that is corrected for turbulence (theimaging beam path incurs turbulence induced aberrations which are thencorrected by the phase correction device 1 110).

Thus, the MO and Probe WFS 120 functions to receive the interferencepatterns of the master oscillator majority beam 100S and minority beam100R and probe majority beam 165M and minority beam 165S using themeasured wavefront error to control the device pair DM2/FSM2 115 toprovide a copy of aberrations of the probe beam (including the laseramplifier 150 aberrations) and MO beam and place them onto DM2/FSM2 pair115. In a similar manner Beacon WFS 124 places aberrations due toturbulence, telescope, relay optics and the beam path onto DM1/FSM1 pair110. In addition, the Beacon WFS 124 inherently also measures theaberrations on the DM2/FSM2 pair 115, and thus also controls theDM1/FSM1 pair 110 to compensate for aberrations in the laser amplifierand master oscillator beam.

In consideration of the beacon beams shown above in FIG. 1 and below inFIGS. 2-5, the beacon beam can be formed from a large number of methodsknown to those skilled in the art. For example, the beacon beam could bea point source, or cooperative beacon, located at the target of interestand directed toward the transmitting system. Alternately, the beaconcould be an illuminator beam launched from an auxiliary telescope toilluminate the target where the reflection from the target serves as thebeacon beam. Alternately, the beacon could be solar illumination of thetarget or thermal emission of the target. If the Target isnon-cooperative, the preferred configuration for the beacon beam that isthe subject of this invention is utilized in FIGS. 6-9 below. It shouldbe noted that mirrors in the optical path are numbered and explainedwhen necessary, other mirrors are provided to show the optical path andmay or may not be labeled.

In consideration of the imaging beam in this invention, the imaging beamcan be formed from a large number of methods known to those skilled inthe art. The imaging beam is only subject to the constraint that it mustenable tracking of the object/target aimpoint for pointing the outgoingHEL beam. For example, if a cooperative point source is available forthe beacon beam, then this beam is also suitable for use as the imagingbeam for use in tracking. Alternately, the imaging beam could be thereturn from active illumination of the target from a laser sourcemounted on an auxiliary aperture, where said return is used to providean image of the target for use in tracking and pointing. Alternately apassive image from solar illumination or thermal emission of the targetcould be used. The distinction between the imaging beam and the beaconbeam is primarily that if the target is “non-cooperative” then theimaging beam must typically be large enough at the target to ensure thatinertial “edges” of the target are imaged and can be used as referencepoints for tracking. In contrast, one typically would prefer the beaconbeam to be as small as possible at the target to provide the highestquality wavefront sensing measurements.

There are two alternate configurations that share the same top leveladvantages as that described by FIG. 1. These are provided in FIG. 2 andFIG. 3.

FIG. 2 is a second alternate schematic of the present inventionillustrating the principle of pre-compensation of phase aberrations bothin a laser amplifier 150 and due to turbulence 180; including correctionof aberrations in the master oscillator beam 100B. The first alternateconfiguration shown in FIG. 2 has the disadvantage that it introduces a3^(rd) steering and phase correction device pair (DM A, FSM A) 222. Thissame configuration, however, has the advantage of providing a moresimplistic and straightforward to understand implementation. Thecompensation of aberrations in the master oscillator beam 100B is by thesame method as that detailed for FIG. 1, while compensation ofaberrations in the amplifier 150 is effected by standard adaptiveoptical system compensation of the probe beam path using DM A and FSM Apair 222 using the signal CC3 from the PRB WFS 220. By compensation ofthe probe beam path, the aberrations in the outgoing high energy laserbeam path are pre-compensated. Due to the nature of amplifieraberrations, which tend to be thermal induced—i.e. large amplitude butlow spatial frequency—the choice of the Probe Wavefront Sensor 220 ishighly flexible. Standard Hartmann sensor technology would be adequateprovided it can meet the necessary closed loop temporal and spatialbandwidth requirements. Any other wavefront sensing technique designedto meet the temporal and spatial bandwidth requirements would beacceptable.

The configuration in FIG. 3 is a third alternate embodiment and isidentical to that in FIG. 2, except for the fact that only two steeringand phase correction device pairs 110, 222 are required because weassume that there are no aberrations in the master oscillator beam 100B.

FIG. 4 is a fourth alternate embodiment schematic of the presentinvention illustrating the principle of pre-compensation of phase andamplitude aberrations both in a laser amplifier 150 and due toturbulence 180; including correction of aberrations in the masteroscillator beam. The configuration described in FIGS. 1-3 provides onlyfor compensation of phase aberrations due to propagation throughturbulence. An alternate method that incorporates compensation of bothamplitude and phase aberrations is illustrated in FIG. 4. This schematicutilizes features from both the configurations described in FIGS. 1, 2.A second pair of phase correction and steering devices DM 1B 425 and DM2B 430 is added to effect amplitude compensation. The opticalpropagation paths are self-explanatory from FIG. 4 with the followingthree details requiring further explanation.

-   -   A. The first point to note is in regard to the “propagation        optics” between the pairs of phase correction and steering        devices. The pair DM 1A, FSM 1A 110 and DM 2A, FSM 2A 115 are        optically conjugate to one another. The pair DM 1B, FSM 1B and        DM 2B, FSM 2B 430 are optically conjugate to one another.        However, there is a free space propagation distance between the        pair 1A/2A (210, 215) and 1B/2B (425, 430) that is effected by        the “propagation optics” 410. There are a number of well known        methods to implement the propagation distance using an optical        configuration. The free space propagation distance is arbitrary,        but past work suggests that the optimal distance for best        correction of both amplitude and phase aberration is roughly        ‘negative D²/λN’ where ‘D’ is the beam size, ‘λ’ is the        wavelength, and ‘N’ is the number of phase correction device        actuator spacings across the beam (ref. 2;3;4).    -   B. The second point to note is in regard to the beam sampling        optic 103 located between the DM1A/FSM1A 210 and DM2A/FSM2A 220        pairs. This beam sampling optic 103, as shown here would be an        optic that splits the light roughly 50% at the beacon        wavelength, while being highly reflective at the HEL wavelength.        The specifications of such an optic are highly application        dependent and not discussed further here. As depicted here,        standard considerations would be adequate for specification of        this optic.    -   C. The third and final point to note is in regard to the        pre-compensation of laser aberrations. Although it is tempting        to think that the interferometric technique described by FIG. 1        can be used herein as well for compensation of laser amplifier        aberrations, use of this technique corrupts the ability to        compensate for amplitude aberrations, thus the amplifier        aberrations are compensated by the technique described in FIG.        2.

The principle of operation of the control system associated with DM/FSMpairs 1B/2B 425, 430 is very similar to that for DM/FSM pairs 1A/2A 210,215:

-   -   1. Measurements on beacon path WFS 415 are        e_(B,B)=φ_(A,B)+c_(1,B)+c_(2,B), where φ_(A,B) is the aberration        induced by propagation through turbulence 180 and the telescope        170 measured at the plane of correction devices DM1B/FSM1B 425        and DM2B/FSM2B 430, c_(1,B) is the correction applied by the        phase correction device DM1B/FSM1B 425, and c_(2,B) is the        correction applied by the phase correction device DM2B/FSM2B        430.    -   2. As a result, the command CC4 that nulls the error, e_(B,B),        is c_(1,B)=−φ_(A,B)−c_(2,B).    -   3. Measurements on the HEL WFS B 420 are        e_(H,B)=φ_(H,B)−c_(2,B), where φ_(H,B) is the aberration on the        HEL master oscillator beam 100B.    -   4. The command CC3 that nulls the signal e_(H,B) is        c_(2,B)=φ_(H,B).    -   5. The command that nulls the error, e_(B,B), is now seen to be        c_(1,B)=−φ_(A,B)−φ_(H,B).

In the case of the operation of the steering device FSM 1B 425, the tiltfrom the beacon WFS B 420 is utilized for high bandwidth control. In thecase of the operation of the steering device FSM 2B 430, the tilt fromthe HEL WFS B 415 is used for high bandwidth control. The issuesassociated with moving atmospheric tilt correction to the steeringdevice SM 160 are only applicable to the first phase correction andsteering device pairs 1A/2A 425, 430.

FIG. 5 is a schematic of the present invention illustrating theprinciple of pre-compensation of phase and amplitude aberrations both ina laser amplifier 150 and due to turbulence 180; excluding correction ofaberrations in the master oscillator beam 100B. In many cases, themaster oscillator beam 100B will have almost no phase aberration. Inthis case, there is no need for the phase correction and steeringdevices DM2B/FSM2B 430 or the HEL WFS B 415 as previously illustrated inFIG. 4 and thus eliminated in FIG. 5. In this case, the phase correctionand steering devices DM1B/FSM1B 425 are controlled in the conventionalmanner from the Beacon WFS B 420.

The reason that the configurations in both FIGS. 4, 5 lead tocompensation of both amplitude and phase aberrations is that underlyingthe electro-optical configuration is an iterative process that can beshown to compensate for both amplitude and phase aberrations. Theunderlying theory is the theory of simultaneous projections ontoconstraint sets, and is described in past work (references 12; 7; 3; 6;5). This theory is related to vector space projection methods foriterative solution of problems that can be cast as a collection ofconvex and non-convex constraint sets.

The schematics described in FIGS. 1-5 describe valid configurations thatcover a wide class of systems. However, the preferred configurationsthat are most suitable for operation with continuous wave high energylaser systems and non-cooperative targets (the primary application ofinterest) are illustrated in FIGS. 6-8, with the latter figureillustrating a configuration that provide compensation only for phaseaberrations and the former two configurations providing compensation forboth phase and amplitude aberrations. A fourth configuration, not shown,is an obvious variation to remove the capacity to compensate foraberrations in the master oscillator beam. All three methods areconfigured in a manner that provides the best possible signal to noiseratio by use of heterodyne detection and provides for an implementationof the method of Target Feature Adaptive Optics (TFAO), which is alimited case of the more general Broadband Coherent Adaptive Optics(BCAO) (8). The primary distinction in these particular embodiments isthat the high energy laser can be either continuous wave or pulsed, butthat an additional high energy beam path which is pre-compensated by aphase correction device labeled DM B and fine steering device labeledFSM B pair 622 in a low power beam path is provided for the beaconilluminator laser.

FIG. 6 is a schematic of the present invention illustrating theprinciple of pre-compensation of phase and amplitude aberrations both ina laser amplifier 150 and due to turbulence 180; ‘including’ correctionof aberrations in the master oscillator beam and including a preferredembodiment for use with non-cooperative targets and continuous wave orpulsed high energy laser beams where the beacon laser master oscillatoris a mode locked short pulse laser 600 and is amplified in a separatebeam path.

The High Energy Laser (HEL) beam path begins with the Master Oscillator100, where the Master Oscillator laser provides the master oscillatorseed beam 100B (also labeled 100S later in the beam path) which is to beamplified by the High Power Amplifier Laser Amplifier (or InjectionLocked Laser Resonator) 150. The master oscillator seed beam 100B isinjected onto the same beam path as the beacon seed beam 600B (alsolabeled 600S later in the beam path) via the aperture sharing element601. The beacon seed beam is generated by the majority sample of thetransform limited mode locked pulsed beacon master oscillator 600 whichis assumed to be linearly polarized. The requirements for the laserpulse length are application dependent and specific to the methods ofTFAO and BCAO, which are detailed further below. For the purpose of thediscussion herein it is sufficient to simply note that relatively shortpulse lengths (typically less than 1 nsec and potentially as short asphysically possible—i.e. fsec class) are assumed. The aperture sharingelement 601 enables sharing the HEL seed beam path and the beacon seedbeam path (i.e. it is shown to be highly reflective at the beacon seedbeam 600B wavelength and highly transmissive at the master oscillatorbeam 100B wavelength—but the converse would be acceptable as well with astandard modification to the drawing in FIG. 6).

After the aperture sharing element 601, the shared beam path 650 of theHEL seed beam 100B is and the beacon seed beam 600B is directed to abeam sampling optic 602. This beam sampling optic is highly reflectiveat the beacon seed beam 600B wavelength and acts as a beam splitter atthe master oscillator beam 100B wavelength. The majority sample of themaster oscillator beam 100B is directed along the shared beam 650 path.The minority sample of the HEL beam, the master oscillator referencebeam 100R, is spatially filtered via the spatial filter optics 145. Thespatial filter optics 145 can be one of any number of methods known tothose skilled in the art, including use of a single mode fiber orpinhole filter. The master oscillator reference beam 100R is then splitinto two paths and directed via standard beam splitters and mirrorsthrough the ‘second’ and ‘fourth’ correction device pairs DM2B/FSM2B 430and DM2A/FSM2A 215 respectively to the aperture sharing elements 603Aand 603B, respectively.

Returning to the shared beam path 650, this beam is directed to theaperture sharing element 603A, which is highly reflective at the beaconseed beam 600B wavelength and acts as a beam splitter at the masteroscillator beam 100B wavelength. The majority of the beam sample of theHEL beam continues on the shared beam path 650, while a minority sampleinterferes with the master oscillator reference beam 100R and isdirected to the ‘fourth’ HEL WFS B 415 where the interference pattern isused to control the ‘second’ correction device pair 430 in the samemanner as that for the configuration described in FIG. 4.

The shared beam path 650 passes through the propagation optics 410 andto the aperture sharing element 603B, which is highly reflective at thebeacon seed beam 600B wavelength and acts as a beam splitter at themaster oscillator (MO) beam 100B wavelength. The majority of the beamsample of the MO beam continues on the shared beam path 650, while aminority sample interferes with the MO reference beam 100R and isdirected to the ‘third’ MO WFS A 120 where the interference pattern isused to control the ‘fourth’ correction device pair DM2A/FSM2A 215 inthe same manner as that for the configuration described in FIG. 1.

The shared beam path 650 passes through the ‘first’ correction devicepair 210 and to the aperture sharing element 604A, which is highlyreflective at the MO beam 100B wavelength and highly transmissive at thebeacon beam 600B wavelength. The HEL beam is directed through the‘fifth’ correction device pair DMA/FSMA 222 through the high poweramplifier (or injection locked laser resonator) 150 to be amplified toform the high power HEL beam 100S, which in turn is directed to theaperture sharing element 604B, which is highly reflective at the MO beam100B wavelength and highly transmissive at the beacon beam 600Bwavelength. The high power HEL beam 100S is directed through the FSM 680and telescope 170, which directs the beam through turbulence 180 to thetarget 190.

The aberrations in the high power amplifier (or injection locked laserresonator) 150 are measured and corrected using the HEL probe beam 165B,which is generated by the HEL probe beam laser 165. The HEL probe beam165B operates in the same manner as that described in FIGS. 2-5 by firstpassing through the high power amplifier (or injection locked laserresonator) 150, then passing through the ‘sixth’ correction device pair222, through the aperture sharing element 604A (which is highlytransmissive at the probe wavelength), and to the ‘fifth’ HEL Probe WFS624. The HEL Probe WFS 624, via control signal CC3, controls the ‘fifth’correction device pair DM2/FSM2 222 using standard methods well known tothose skilled in the art.

Returning to the aperture sharing element 604A, the beacon beam 600B(also labeled 600S) passes through this optic and is directed to thepolarizing beam splitter 605A. It is noted that prior to the polarizingbeam splitter 605A, the beacon beam 600B has “S” polarization and thusis reflected from the polarizing beam splitter 605A and directed throughthe ‘sixth’ correction device pair DMB/FSMB 622 and then amplified viathe medium power (where medium is defined as having sufficientamplification to be used as a beacon beam) amplifier (or injectionlocked laser resonator) 660 to form the high power beacon beam 600HS.High power beacon beam 600HS reflects off of the aperture sharingelement 606 which is highly reflective at the beacon beam 600HSwavelength and highly transmissive at the beacon probe beam 665Bwavelength.

The aberrations in the medium power amplifier (or injection locked laserresonator) 660 are measured and corrected using the beacon probe beam665B, which is generated by the beacon probe beam laser 665. The beaconprobe beam 665B operates in the same manner as that described in FIGS.2-5 by first passing through the medium power amplifier (or injectionlocked laser resonator) 660, then passing through the ‘sixth’ correctiondevice pair DMB/FSMB 622, through the polarizing beam splitter 605A(which is highly transmissive at the probe wavelength), and to the‘sixth’ Beacon Probe WFS 620. The Beacon Probe WFS 620, via controlsignal CC6, controls the correction device pair DMB/FSMB 622 usingstandard methods well known to those skilled in the art.

Returning to aperture sharing element 606, the high power beacon beam600HS is directed to the polarizing beam splitter 605B where the beaconbeam 600HS, which remains “S” polarized, then reflects and is directedthrough the quarter waveplate 710. The quarter waveplate 710 convertsthe high power beacon beam 600HS to circular polarization so that afterpropagating to the target 190 (through the aperture sharing element604B, FSM 680, telescope 170, and turbulence 180) and back the returnbeacon beam 106B will be converted back to “P” polarization and willtransmit through the polarizing beam splitter 605B. The particulars oftarget interaction of the pulse are discussed below in the discussion ofTarget Feature Adaptive Optics (TFAO).

After the return beacon beam 106B transmits through the polarizing beamsplitter 605B, the beam is imaged via relay optics 140 so that thereturn beam has the same longitudinal conjugate plane as the outgoingbeacon beam 600B at the plane of the polarizing beam splitter 605A.Because the return beacon beam 106B at this point retains “P”polarization, the return beacon beam 106B transmits through thepolarizing beam splitter 605A. The return beacon beam 106B continuesthrough the ‘first’ correction device pair DM1A/FSM1A 210 and to theaperture sharing element 603B. It is to be noted at this point thataperture sharing element 603B is optimally designed such that it ishighly reflective at “S” polarization at the beacon laser 600wavelength, but roughly 50% transmissive and 50% reflective at the “P”polarization at the beacon laser 600 wavelength (where the transmit toreceive ratio at “P” polarization should be optimized depending on theexact system configuration). In so doing, aperture sharing element 603Bmaximizes outgoing beam throughput on the beacon path, but acts as anappropriate beam splitter on the return path.

The first of the two samples of the return beacon beam 106B is directedthrough ‘fourth’ correction device pair DM2A/FSM2A 215 to the ‘first’Beacon wavefront sensor WFS A 124. In WFS A 124, the return beam isinterfered according to the method of Broadband Coherent Adaptive Optics(BCAO) or Target Feature Adaptive Optics (TFAO) with a local oscillatorpulse 600R from the mode locked beacon master oscillator 600 asdescribed in the text below. The second sample of the return beacon beam106B is directed through the propagation optics 410 and ‘third’correction device pair DM1B/FSM1B 425 to aperture sharing element 603Awhich shares the same properties as aperture sharing element 603B.Noting that the sample of the return beacon beam 106B remains in the “P”polarization state, the beam transmits through the aperture sharingelement 603A, and to the ‘second’ Beacon wavefront sensor WFS B 420 viathe ‘second’ correction device pair DM2B/FSM2B 430, where as with thefirst sample of the beacon return beam 106B, the beam is interferedaccording to the method of Broadband Coherent Adaptive Optics (BCAO) orTarget Feature Adaptive Optics (TFAO) with a local oscillator pulsebeacon reference beam 600R from the mode locked beacon master oscillator600 as described in the text below.

The majority sample of the mode locked beacon master oscillator 600 wasreferenced above and traced through the system to the target and backfor interference with a minority sample of the mode locked beacon masteroscillator 600. The minority sample beam, the beacon reference beam600R, is directed into a Beacon WFS A 124 for use in heterodynedetection of the received signal. In the case of FIG. 6 the minoritysample of the beam 600R is directed into both Beacon WFS A 124 andBeacon WFS B 420 according to the method of Broadband Coherent AdaptiveOptics (BCAO) or Target Feature Adaptive Optics (TFAO). This particularconfiguration assumes that the minority sample of the beam referencebeam 600R is actually sampled from a very high repetition rate (order 10MHz or more) sub-master mode locked beacon master oscillator 600 (thissub-master mode locked beacon master oscillator 600 would serve as aseed laser for an amplifier internal to the device labeled “mode lockedbeacon master oscillator” 600 which in order to support atmosphericcompensation would typically have repetition rates from 5 to 50 kHz—thisframe rate is based on requirements for compensation and is not confinedto this range of frame rates). Standard heterodyne detection methods canbe utilized and multiple approaches can be adopted, but a particularconfiguration is described below that includes optical delay circuitryto account for the time delay between pulses.

The principle of the real time control algorithm is the same as that forthe schematic described in FIG. 4 and the same properties are shared,with the difference being in FIG. 6 that the preferred embodiment hasbeen described which utilizes the method of BCAO or TFAO to form adiffraction limited size beacon beam 600HS at the target 190 along withheterodyne detection to achieve maximum signal to noise ratio and tointerferometrically range gate the target aimpoint onto the beaconwavefront sensors WFS A 124 and WFS B 420. As such, the preferredembodiment illustrated in FIG. 6 provides a method that is suitable fornon-cooperative targets for pre-compensation of a low power seed beamfor aberrations induced by propagation through both turbulence and ahigh power amplifier.

FIG. 7 is a schematic illustrating the principle of pre-compensation ofphase and amplitude aberrations both in a laser amplifier and due toturbulence; ‘excluding’ correction of aberrations in the masteroscillator beam 100B and including a preferred embodiment for use withnon-cooperative targets and continuous wave or pulsed high energy laserbeams where the beacon laser master oscillator 600 is a mode lockedshort pulse laser and is amplified in a separate beam path. FIG. 7 issimilar to FIG. 6 with the exception that the DM2 B/FSM 2B pair 430 isremoved.

FIG. 8 is a schematic illustrating the principle of pre-compensation ofphase aberrations both in a laser amplifier and due to turbulence;including correction of aberrations in the master oscillator beam andincluding a preferred embodiment for use with non-cooperative targetsand continuous wave or pulsed high energy laser beams where the beaconlaser master oscillator is a mode locked short pulse laser and isamplified in a separate beam path. FIG. 8 is similar to FIG. 7 with theexception that the propagation optics 410, beacon WFS B 420 andDM1B/FSMB pair 425 are removed.

Up to this point the discussion has not detailed methods for processingdata and real time control. There are multiple options for real timecontrol and specifics of the application will define the best method.The standard “least squares unwrapping method with branch pointaddition” combined with the exponential filter control algorithm islikely the most straightforward candidate for implementation (ref. 4;8). This algorithm would be applied to each control loop. Theparticulars of design of control coefficients would utilize well knownand standard techniques.

The preceding discussion completes the technical description of theILFCS, providing both a top level conceptual description as well as amore detailed description of a likely preferred configuration. It shouldbe noted that the distinct advantage of the method of the presentinvention is that all of the phase correction devices can be in lowerpower beam paths, greatly reducing requirements on a high costcomponents that also will typically drive the overall size of the beamcontrol system. The ILFCS and its derivative sub-methods represent arevolutionary approach to beam control for propagation of lasers and canbe used for a wide range of applications. The ILFCS as described hereinis effective for a wide range of cooperative target applications and iseffective with non cooperative targets using a pre-compensated beaconlaser without the added complexity of heterodyne TFAO or BCAO at modestranges (typically if the range and turbulence strength is such that thespherical wave Rytov number, R, is less than about 0.7. The Rytovnumber, R, is defined as:

${R = {0.5631\left( \frac{2\;\pi}{\lambda} \right)^{7/6}{\int_{0}^{L}\ {{\mathbb{d}{{zz}^{5/6}\left( {1 - \frac{z}{L}} \right)}^{5/6}}{C_{n}^{2}(z)}}}}},$

-   -   where λ is the wavelength of propagation, z is the slant path        variable, L is the propagation slant range, and C_(n) ²(z) is        the refractive index structure constant along the propagation        path. It should be noted that by the word “effective” is meant        that the ILFCS will achieve performance nearly as good as that        for a cooperative point source beacon, but will not quite        achieve this full performance due to various error sources that        are not avoidable, but are well minimized by the use of a        compensated beacon in conjunction with the ILFCS method or its        derivative methods.

FIG. 9A is a drawing illustrating the principle of Broadband CoherentAdaptive Optics (BCAO), of which Target Feature Adaptive Optics (TFAO)is a special case, using a mode locked master oscillator seed laserwhich has transform limited pulses. Shown are telescope 170, turbulence180, outgoing pulse train 820, pulse delay circuitry 905, and target190. FIG. 9B below will describe the configuration in more detail.

FIG. 9B is a schematic representing the drawing of FIG. 9A andillustrating the principle of Broadband Coherent Adaptive Optics (BCAO),of which Target Feature Adaptive Optics (TFAO) is a special case, usinga mode locked master oscillator seed laser which has transform limitedpulses. A reference pulse is interfered with the pulse return from thetarget to select a precise location on the target 170 for wavefrontsensing along the axis of propagation. If the target 170 has depth, thenthe sub-method of TFAO is adequate, providing reduced spatial extent ofthe beacon spot formed on the target. If the target is relatively flatthen the full method of BCAO is required. In this case, the fringesoutside the central core of the spot formed over the bandpass of theultra short pulse wash out, leading to a near diffraction limitedfocused spot at the target 170. The previous discussion focused on theparticulars of the optical configuration(s) that can be used to achievepre-compensation of aberrations both in the laser gain medium and forpropagation through turbulence. In FIGS. 9-12, is discussed detail on aparticular configuration for implementation of a method (ref. 8) to forma diffraction limited size beacon on a non-cooperative target denotedBroadband Coherent Adaptive Optics (BCAO), of which Target FeatureAdaptive Optics (TFAO) is a special, but less capable. The particularnew configuration described here represents the preferred method toimplement BCAO or TFAO.

The basic configuration is illustrated in FIGS. 9A, 9B. The outgoingshort beacon pulse train 920 from the mode locked master oscillator 600having transform limited pulses is transmitted through optic 912 and theILFCS optics 915 and beam train, through the telescope 170, turbulence180 and to the target 190 where it reflects back from the target 190 andreturns through the turbulence 180, telescope 170, optic 912, ILFCSoptics 915, and waveplate 910 at an orthogonal polarization to theoriginal launched beam. This beam is then interfered with a referencepulse train 925 from the mode locked master oscillator 600, with thetiming of the delay circuitry 905 controlling the reference pulse 925 toonly interfere with the pulse return at optic 940 and becomes compositebeam 922 corresponding to a precise location on the target 190 along theaxis of propagation of the laser. In so doing, if there are features onthe target 190, then the spatial extent of the pulse that actually isused for phase measurement is reduced simply by the target geometry asillustrated in FIG. 9. This provides a small beacon, whose extent islimited by: (1) the length of the pulse; and (2) ensuring that adequatesignal to noise is provided. The length of the pulse can be veryshort—for many typical targets 10-100 psec pulses are adequate althoughpulse length ranges can be from about 1 picosecond to about 1000picoseconds. If the target is completely or nearly flat then femtosecondclass pulse lengths are required in order to effect the method ofBroadband Coherent Adaptive Optics of reference [8]. Adequate signal tonoise is provided by use of the local oscillator to boost theinterference fringes into the shot noise limit of the detector,providing the maximum possible range, given finite laser power. If thetarget 190 is near flat or featureless with no depth in the region ofinterest, then the pulse length must be very short, and ideally shouldbe so short such that fringes outside the central core of the focusedbeam destructively interfere and wash out all but the centralcore—forming a nearly diffraction limited spot from the perspective ofthe wavefront sensor 930. This is the method of BCAO, with TFAO being aless capable sub-case (ref. 8).

The wavefront sensor optics are only shown generically in FIG. 9. Twospecific example implementations are provided in FIGS. 10, 11.

FIG. 10 is a schematic for the wavefront sensor optics for the method ofTFAO or BCAO defined in FIG. 9. The reference and return pulse are atorthogonal polarizations and thus a properly aligned partial retardancewaveplate 962 (aligned to the “s” polarization of the reference pulsetrain) applies the necessary phase shifts to obtain a 3-bin spatialphase shifting interferometer. FIG. 10 illustrates a purely spatialphase shifting 3-bin interferometer implementation. Non-polarizingapproximately 50% beam splitters 924, 926, direct composite beam 922through waveplates 960A, 960B, 960C and polarizers 950A, 950B, 950C tocameras 990A, 990B, and 990C respectively. The schematic is largelyself-explanatory, given knowledge that the reference signal and thereturn signal are at orthogonal polarizations and that the π/3 waveplate960A, 5/3π waveplate 960B, π waveplate 960C associated with each camera990A, 990B, 990C respectively can be aligned to the axis of polarizationof the reference beam. This first method has the limitation that itwastes roughly half of the signal.

FIG. 11 is a schematic for an alternate sub-optimal implementation ofwavefront sensor optics for the method of TFAO or BCAO defined in FIG.6. The reference and return pulse are at orthogonal polarizations. Theuse of polarizing splitter 970 and appropriately aligned waveplates 962,962A provides measurements of the phase with 0 and π phase shifts at thedetector. The phase modulator 980 is toggled rapidly between 0 and π/2,with the latter position providing π/2 and 3π/2 phase shift measurementsat the detectors. In this configuration, two phase shift measurementsare obtained for a given pulse return, with a second pair obtained atalternating pulse returns. The first pair obtained would correspond to 0and π phase shift measurements, while the second pair obtained wouldcorrespond to π/2 and 3π/2 phase shift measurements by applying a π/2phase shift to the reference beam path 925 on alternating pulses. Thereis a performance degradation due to this method if the piston phase ofthe return signal or the reference signal varies significantly frompulse to pulse (a likely scenario).

FIG. 12 is a schematic of the preferred implementation for the wavefrontsensor optics for the method of TFAO or BCAO defined in FIG. 6. Thereference and return pulse are at orthogonal polarizations and thediagram here forms a 4-bin spatial phase shifting interferometer. Giventhat the method in FIG. 10 wastes roughly half of the signal (but wouldbe a viable solution) and given that the configuration in FIG. 11 likelywill have poor performance due to pulse to pulse variations in thepiston of the return or reference pulse, the preferred implementation isdepicted in FIG. 12. In this method showing half waveplates 962, 965A,and 965B, quarter waveplate 964, polarizing splitters 970, 970B, and970C, and non-polarizing approximately 50% beam splitter 970A, there isno wasted light, providing the best possible signal to noise ratio.Although illustrated with four cameras 990A, 990B, 990C, 990D, theselection of 1, 2, or 4 cameras would be subject to engineering andimplementation trades (maximum speed would be obtained with 4 cameras,but this will lead to a more expensive and larger system).

Thus, referring to FIGS. 6, 9, 12, the preferred embodiment of thepresent invention would consist of the following for projection of laserbeams through a turbulent medium to a non-cooperative target:

-   -   1) a master oscillator beam 100B having an optical path to a        high power laser amplifier 150 or injection locked laser        amplifier forming a high energy laser (HEL) beam to a target 190        via an optical path including a steering mirror 680 and a        telescope 170;    -   2) a mode locked beacon master oscillator 600 that produces a        majority sample high repetition rate (ranging from about 100 to        100000 Hz) sequence of transform limited pulsed laser beams and        a minority reference beam has a repetition rate defined by the        cavity length of the mode locked oscillator (ranging typically        from MHz to GHz);    -   3) a timing delay circuit 905 which receives the reference beam        600R and produces a delayed reference beam 925 that is delayed        to coincide with the arrival of the return beacon signal pulse        from the target aimpoint along the propagation path axis;    -   4) the majority high repetition rate beacon beam transmitted via        an optical path to a medium power amplifier 660 which sends a        beacon beam via an optical path to the target 190;    -   5) the high repetition rate reflected (return) beacon pulse        train beam returns from the target 190 through the turbulent        medium 180, telescope 170, optical path, and a quarter waveplate        710 in the optical path, then passes through a first polarizing        wave splitter optic 605A and is then directed to a first beacon        wave front sensor (WFS) 124 where it is combined and        subsequently interfered with the reference beam 600R for phase        measurement;    -   6) the first WFS controlling a first phase correction and        steering device pair 210 which (1) corrects the majority beacon        beam with respect to phase aberrations caused by propagation        through the turbulent medium 180 and (2) provides phase commands        to the first correction and steering device pair 210 that will        result in correction of amplitude aberrations in the beacon beam        caused by propagation through the turbulent medium;    -   7) a tracker and aim point controller 107 which receives an        image of the target, thereby generating a control signal CCFSM        to control the steering mirror 680;    -   8) the minority beacon beam further comprising a segment which        goes to a second beacon WFS 420 which also receives a segment of        the return beacon beam 105B after said returning beacon beam        passes through a further propagation optics and a third and        second correction and steering device pair 425, 430;    -   9) the second beacon WFS 420 controlling a third correction and        steering device pair 425 corrects for remaining aberrations in        the beacon beam, resulting in correction of both amplitude and        phase aberrations caused by propagation through the turbulent        medium;    -   10) a third WFS 120 receives a sample beam from the minority        master oscillator beam to compare to a sample of the majority        master oscillator beam after it passes through an optical path        including a propagation optics and the third correction and        steering device pair and controls a fourth correction and        steering device pair for aberrations induced by propagation        through the third phase correction and steering device pair 425        and propagation optics 410;    -   11) a fourth WFS 415 receives a sample of the majority master        oscillator beam and a minority master oscillator beam after it        passes through a spatial filter optic 145 and the second        correction and steering device pair 430 and controls a second        phase correction and steering device pair 430 for aberrations in        the master oscillator 100;    -   12) a fifth WFS 624 receiving a HEL amplifier probe beam 165B        after it passes through the HEL amplifier 150, controls a fifth        correction and steering device pair 222.

The methods shown above in FIGS. 10, 11, 12, are shown by way of exampleand not of limitation as these are not the only three methods that couldbe utilized. There are many approaches suitable for optimalimplementation. For example, if the camera integration time and triggertime could be controlled to sub-psec levels, then a heterodyne approachwould not be required. The heterodyne approach is required to enablecontrol over the depth of the target of the location of the pulse returngiven currently available camera technology. New developing so-calledtime-of-flight cameras could enable non-heterodyne approaches, however,the signal to noise ratio is likely best for a heterodyne approach,regardless. The combination of a time-of-flight camera with theheterodyne approach is many years from current technology, but wouldprovide the best possible signal to noise ratio and performance, given aspecific detector read noise by reducing background shot noise.

As a final point, if the master oscillator for the beacon laser iscarrier envelope phase stabilized (a mode locked laser may still havedrift in the carrier envelope phase), then multiple pulses can beintegrated in a single detection. The requirement for carrier envelopephase stabilization in this case would be that the carrier envelopephase be stable over the length of the integration time. The advantageof taking this approach would be that a higher repetition rate lasercould be utilized, reducing the peak power of the illuminator pulses,and thus reducing demand on optical coatings in the system andminimizing the probability of non-linear propagation effects becomingsignificant.

Note that requirements on the optical delay circuitry are driven not bythe round trip time of flight, but rather on the combination of theround trip time of flight and the high repetition rate sub-masteroscillator. The repetition rate of these devices is typically in the 100MHz class, and thus the longest possible time of flight that must beadjusted is the delay time between pulses. A binary fiber circuit withmultiple length delay lines combined with a piston mirror orelectro-optic phase modulator would provide control from coarse to veryfine. This would not be a difficult or complex system to develop andwould be readily developed by many potential companies given targetstate data with accuracy consistent with requirements for aimpointprecision.

FIG. 13 is a chart showing the normalized beam profile and normalizedcumulative power in the bucket as a function of bucket diameter and arefractive index. Shown as an example is a beam profile and cumulativepower in the bucket as a function of bucket diameter for an 8 kmhorizontal path with a uniform distribution of the strength ofturbulence and a refractive index structure constant, C_(n) ²=1e−14m^(−2/3). Performance of the ILFCS with TFAO is an order of magnitudeimproved relative to conventional techniques—and the performance usingILFCS with TFAO is equivalent to that achieved using a point sourcebeacon (where a point source beacon would be the optimal beacon). TheILFCS of the present invention has been simulated for a range ofapplications. A significant performance improvement over conventionaltechniques due to the ILFCS is consistently observed. The majority ofthe benefit is due to the use of BCAO/TFAO. The benefits of the laseraberration pre-compensation aspect of the ILFCS are primarily associatedin reduction of size, weight, and power of the beam control and overallsystem. The performance shown does not reach the fitting error limit dueto losses due to servo lag (inadequate correction speed for thisparticular example) and due to fundamental limitations, but results inan order of magnitude performance improvement over conventionaltechniques.

The ILFCS offers tremendous enabling potential for a broad range ofapplications. Eliminating the requirement that the phase correctiondevice be in the high power beam path offers significant reductions insize, weight, and power handling of the system and eliminates the riskassociated with equipping a system with a high energy laser with a phasecorrection device that could be damaged or destroyed by the high energylaser. The ILFCS is likely most compatible with solid state lasers in amaster oscillator power amplifier configuration in the near term, butover time may be proven to be more compatible with unstable resonatorsusing injection locking and/or using the unstable resonator geometrysimply as a multi-pass amplifier.

Although the present invention has been described with reference topreferred embodiments, numerous modifications and variations can be madeand still the result will come within the scope of the invention. Nolimitation with respect to the specific embodiments disclosed herein isintended or should be inferred. Each apparatus embodiment describedherein has numerous equivalents.

I claim:
 1. An electro-optical system for projection of laser beamsthrough a turbulent medium to a non-cooperative target, the systemcomprising: a) a master oscillator beam having an optical path to anamplifier means; b) said amplifier means forming a high energy laser(HEL) beam to a target via an optical path; c) said optical pathincluding a steering mirror and a telescope; d) a mode locked beaconmaster oscillator that produces a majority beacon beam comprising a highrepetition rate (ranging from about 100 to 100000 Hz) sequence oftransform limited pulsed laser beams and producing a minority referencebeam that has a repetition rate defined by the cavity length of the modelocked beacon master oscillator (ranging typically from MHz to GHz); e)wherein a timing delay circuit receives the minority reference beam andproduces a delayed reference beam that is delayed to coincide with thearrival of a return beacon beam from a target aimpoint along apropagation path axis; f) said majority beacon beam transmitted via anoptical path to a medium power amplifier which sends the majority beaconbeam via an optical path to the target; g) wherein a return beacon beamcomprising a high repetition rate pulse train beam returns from thetarget through the turbulent medium, telescope, optical path, and aquarter waveplate in the optical path, then passes through a firstpolarizing wave splitter optic; h) wherein the return beacon beam isthen directed to a first beacon wave front sensor (WFS) where it iscombined with the minority reference beam to form a composite beam forphase measurement; i) said first WFS controlling a first phasecorrection and steering device pair which (1) corrects the majoritybeacon beam with respect to phase aberrations caused by propagationthrough the turbulent medium and (2) provides phase commands to thefirst phase correction and steering device pair that will result incorrection of amplitude aberrations in the beacon beam caused bypropagation through the turbulent medium; j) a tracker and aim pointcontroller which receives an image of the target from an illuminationsource, thereby generating a control signal to control the steeringmirror; k) a third WFS (no second WFS is named) receives a sample beamfrom the minority master oscillator beam after it passes through aspatial filter optic and the fourth correction and steering device pairto compare to a sample of the majority master oscillator beam after itpasses through an optical path including a propagation optics and thethird correction and steering device pair (no second correction andsteering device par is named); l) said third WFS controlling a fourthcorrection and steering device pair to correct for aberrations inducedby propagation through the third phase correction and steering devicepair and propagation optics; m) a fifth WFS receiving a HEL amplifierprobe beam after it passes through the amplifier means; and n) saidfifth WFS controlling a fifth correction and steering device pair. 2.The system of claim 1, wherein the first and fourth pair of phasecorrection and steering device pairs are optically conjugate to oneanother.
 3. The system of claim 1, wherein the third pair of phasecorrection and steering device pairs have a free space propagationdistance (from the conjugate plane of the first and fourth phasecorrection and steering device pairs) of approximately:−D ² /λN where D is the beam size, X is the wavelength and N is thenumber of phase correction device actuator spacings across the beam. 4.The system of claim 1, wherein the beacon beam is formed as acooperative beacon located at the target and pointed toward thetransmitting HEL optical path.
 5. The system of claim 1, wherein thebeacon beam is formed as an illuminator beam launched from an auxiliarytelescope to illuminate the target, and the reflection from the targetserves as the beacon beam.
 6. The system of claim 1, wherein the beaconbeam is a solar illumination of the target.
 7. The system of claim 1,wherein the beacon beam is a thermal emission of the target.
 8. Thesystem of claim 1, wherein the amplifier means is an injection lockedlaser resonator.
 9. The system of claim 1, wherein the image of thetarget is formed as a cooperative beacon located at the target andpointed toward the transmitting HEL optical path.
 10. The system ofclaim 1, wherein the image of the target received by the aim pointcontroller is either a passive or active illumination of the target. 11.The system of claim 1, wherein a sixth WFS receives a beacon amplifierprobe beam after it passes through a beacon medium power amplifier andalso receives a sample beam from the beacon amplifier probe beam. 12.The system of claim 11, wherein the sixth WFS controls a sixthcorrection and steering device pair.
 13. The system of claim 1, whereinthe amplifier means is a high power laser amplifier.
 14. The system ofclaim 1, wherein the amplifier means is an injection locked laseramplifier.
 15. The electro-optical system of claim 1, wherein a firstpart of the composite beam is directed to a half waveplate that rotatesthe polarization of the composite beam by 45 degrees and then to apolarizing beam splitter that directs the resultant interferencepatterns to a first and second camera with the resulting measurementsbeing used to compute an estimate of a real part of a measured complexfield of the return beacon beam.
 16. The electro-optical system of claim1, wherein a second part of the composite beam is directed first to aquarter waveplate with its crystal axis aligned to the polarization axisof the minority reference beam and then to a half waveplate that rotatesthe polarization of the composite beam by 45 degrees and then to apolarizing beam splitter that directs the resultant interferencepatterns to a third and fourth camera with the resulting measurementsbeing used to compute an estimate of an imaginary part of a measuredcomplex field of the return beacon beam.
 17. The electro-optical systemof claim 1, wherein the minority reference beam and the return beaconbeam are at orthogonal polarizations to one another.
 18. Theelectro-optical system of claim 1, wherein the first and second WFSconsists of a π/3 waveplate, a 5/3π waveplate, and a π waveplate eachassociated with a separate camera and can be aligned to the axis ofpolarization of the minority reference beam.
 19. An electro-opticalsystem for projection of laser beams through a turbulent medium to anon-cooperative target, the system comprising: a) a mode locked beaconmaster oscillator that produces a majority beacon beam comprising a highrepetition rate (ranging from about 100 to 100000 Hz) sequence oftransform limited pulsed laser beams (a beacon beam) and producing aminority reference beam that has a repetition rate defined by the cavitylength of the mode locked beacon master oscillator (ranging typicallyfrom MHz to GHz); b) said mode locked beacon master oscillator beamhaving an optical path to an amplifier means; c) said amplifier meansforming a high energy laser (HEL) beam to a target via an optical path;d) said optical path including a steering mirror and a telescope; e)wherein a timing delay circuit receives the minority reference beam andproduces a delayed reference beam that is delayed to coincide with thearrival of a return beacon beam from a target aimpoint along apropagation path axis; f) said majority beacon beam transmitted via anoptical path to a medium power amplifier which sends the majority beaconbeam via an optical path to the target; g) wherein a return beacon beamcomprising a high repetition rate pulse train beam returns from thetarget through the turbulent medium, telescope, optical path, and aquarter waveplate in the optical path, then passes through a firstpolarizing wave splitter optic; h) wherein the return beacon beam isthen directed to a first beacon wave front sensor (WFS) where it iscombined with the minority reference beam to form a composite beam forphase measurement; i) said first WFS controlling a first phasecorrection and steering device pair which (1) corrects the beacon beamwith respect to phase aberrations caused by propagation through theturbulent medium and (2) provides phase commands to the first phasecorrection and steering device pair that will result in correction ofamplitude aberrations in the beacon beam caused by propagation throughthe turbulent medium; j) a tracker and aim point controller whichreceives an image of the target from an illumination source, therebygenerating a control signal to control the steering mirror; k) a thirdWFS (no second WFS is named) receives a sample beam from the minorityreference beam after it passes through a spatial filter optic and thefourth correction and steering device pair to compare to a sample of themajority beacon beam after it passes through an optical path including apropagation optics and the third correction and steering device pair (nosecond correction and steering device par is named); l) said third WFScontrolling a fourth correction and steering device pair to correct foraberrations induced by propagation through the third phase correctionand steering device pair and propagation optics; m) a fifth WFSreceiving a HEL amplifier probe beam after it passes through theamplifier means; and n) said fifth WFS controlling a fifth correctionand steering device pair.
 20. The system of claim 19, wherein the firstand fourth pair of phase correction and steering device pairs areoptically conjugate to one another; wherein the third pair of phasecorrection and steering device pairs have a free space propagationdistance (from the conjugate plane of the first and fourth phasecorrection and steering device pairs) of approximately:−D ² /λN where D is the beam size, λ is the wavelength and N is thenumber of phase correction device actuator spacings across the beam;wherein the image of the target is formed as a cooperative beaconlocated at the target and pointed toward the transmitting HEL opticalpath; and wherein the image of the target received by the aim pointcontroller is either a passive or active illumination of the target. 21.The system of claim 19, wherein the amplifier means is a high powerlaser amplifier.
 22. The system of claim 19, wherein the amplifier meansis an injection locked laser amplifier.
 23. The system of claim 19,wherein a first part of the composite beam is directed to a halfwaveplate that rotates the polarization of the composite beam by 45degrees and then to a polarizing beam splitter that directs theresultant interference patterns to a first and second camera with theresulting measurements being used to compute an estimate of a real partof a measured complex field of the return beacon beam; wherein a secondpart of the composite beam is directed first to a quarter waveplate withits crystal axis aligned to the polarization axis of the minorityreference beam and then to a half waveplate that rotates thepolarization of the composite beam by 45 degrees and then to apolarizing beam splitter that directs the resultant interferencepatterns to a third and fourth camera with the resulting measurementsbeing used to compute an estimate of an imaginary part of a measuredcomplex field of the return beacon beam; wherein the minority referencebeam and the return beacon beam are at orthogonal polarizations to oneanother; and wherein the first and second WFS consists of a π/3waveplate, a 5/3π waveplate, and a π waveplate each associated with aseparate camera and can be aligned to the axis of polarization of theminority reference beam.